Largest product in a grid

Largest product in a grid is a draft programming task. It is not yet considered ready to be promoted as a complete task, for reasons that should be found in its talk page.

Task

The task description is taken from Project Euler:
(https://projecteuler.net/problem=11)

Given the 20×20 grid below:

08 02 22 97 38 15 00 40 00 75 04 05 07 78 52 12 50 77 91 08
49 49 99 40 17 81 18 57 60 87 17 40 98 43 69 48 04 56 62 00
81 49 31 73 55 79 14 29 93 71 40 67 53 88 30 03 49 13 36 65
52 70 95 23 04 60 11 42 69 24 68 56 01 32 56 71 37 02 36 91
22 31 16 71 51 67 63 89 41 92 36 54 22 40 40 28 66 33 13 80
24 47 32 60 99 03 45 02 44 75 33 53 78 36 84 20 35 17 12 50
32 98 81 28 64 23 67 10 26 38 40 67 59 54 70 66 18 38 64 70
67 26 20 68 02 62 12 20 95 63 94 39 63 08 40 91 66 49 94 21
24 55 58 05 66 73 99 26 97 17 78 78 96 83 14 88 34 89 63 72
21 36 23 09 75 00 76 44 20 45 35 14 00 61 33 97 34 31 33 95
78 17 53 28 22 75 31 67 15 94 03 80 04 62 16 14 09 53 56 92
16 39 05 42 96 35 31 47 55 58 88 24 00 17 54 24 36 29 85 57
86 56 00 48 35 71 89 07 05 44 44 37 44 60 21 58 51 54 17 58
19 80 81 68 05 94 47 69 28 73 92 13 86 52 17 77 04 89 55 40
04 52 08 83 97 35 99 16 07 97 57 32 16 26 26 79 33 27 98 66
88 36 68 87 57 62 20 72 03 46 33 67 46 55 12 32 63 93 53 69
04 42 16 73 38 25 39 11 24 94 72 18 08 46 29 32 40 62 76 36
20 69 36 41 72 30 23 88 34 62 99 69 82 67 59 85 74 04 36 16
20 73 35 29 78 31 90 01 74 31 49 71 48 86 81 16 23 57 05 54
01 70 54 71 83 51 54 69 16 92 33 48 61 43 52 01 89 19 67 48

What is the greatest product of four adjacent numbers in the same direction (down, right) in the 20×20 grid?

11l

Translation of: Python

F maxproduct(mat, length)
   ‘ find the largest product of len length horizontal or vertical length in matrix ’
   V (nrow, ncol) = (mat.len, mat[0].len)
   V (maxprod, maxrow, maxcol, arr) = (Int64(0), [0, 0], [0, 0], [0])
   L(row) 0 .< nrow
      L(col) 0 .< ncol
         V (row2, col2) = (row + length, col + length)
         I row < nrow - length
            V array = mat[row .< row2].map(r -> r[@col])
            V pro = product(array.map(Int64))
            I pro > maxprod
               (maxprod, maxrow, maxcol, arr) = (pro, [row, row2], [col], array)
         I col < ncol - length
            V pro = product(mat[row][col .< col2].map(Int64))
            I pro > maxprod
               (maxprod, maxrow, maxcol, arr) = (pro, [row], [col, col2], mat[row][col .< col2])

   print(‘The max ’length‘-product is ’maxprod‘, product of ’arr‘ at row ’maxrow‘, col ’maxcol‘.’)

V MATRIX = [
    [ 8,  2, 22, 97, 38, 15,  0, 40,  0, 75,  4,  5,  7, 78, 52, 12, 50, 77, 91,  8],
    [49, 49, 99, 40, 17, 81, 18, 57, 60, 87, 17, 40, 98, 43, 69, 48,  4, 56, 62,  0],
    [81, 49, 31, 73, 55, 79, 14, 29, 93, 71, 40, 67, 53, 88, 30,  3, 49, 13, 36, 65],
    [52, 70, 95, 23,  4, 60, 11, 42, 69, 24, 68, 56,  1, 32, 56, 71, 37,  2, 36, 91],
    [22, 31, 16, 71, 51, 67, 63, 89, 41, 92, 36, 54, 22, 40, 40, 28, 66, 33, 13, 80],
    [24, 47, 32, 60, 99,  3, 45,  2, 44, 75, 33, 53, 78, 36, 84, 20, 35, 17, 12, 50],
    [32, 98, 81, 28, 64, 23, 67, 10, 26, 38, 40, 67, 59, 54, 70, 66, 18, 38, 64, 70],
    [67, 26, 20, 68,  2, 62, 12, 20, 95, 63, 94, 39, 63,  8, 40, 91, 66, 49, 94, 21],
    [24, 55, 58,  5, 66, 73, 99, 26, 97, 17, 78, 78, 96, 83, 14, 88, 34, 89, 63, 72],
    [21, 36, 23,  9, 75,  0, 76, 44, 20, 45, 35, 14,  0, 61, 33, 97, 34, 31, 33, 95],
    [78, 17, 53, 28, 22, 75, 31, 67, 15, 94,  3, 80,  4, 62, 16, 14,  9, 53, 56, 92],
    [16, 39,  5, 42, 96, 35, 31, 47, 55, 58, 88, 24,  0, 17, 54, 24, 36, 29, 85, 57],
    [86, 56,  0, 48, 35, 71, 89,  7,  5, 44, 44, 37, 44, 60, 21, 58, 51, 54, 17, 58],
    [19, 80, 81, 68,  5, 94, 47, 69, 28, 73, 92, 13, 86, 52, 17, 77,  4, 89, 55, 40],
    [ 4, 52,  8, 83, 97, 35, 99, 16,  7, 97, 57, 32, 16, 26, 26, 79, 33, 27, 98, 66],
    [88, 36, 68, 87, 57, 62, 20, 72,  3, 46, 33, 67, 46, 55, 12, 32, 63, 93, 53, 69],
    [ 4, 42, 16, 73, 38, 25, 39, 11, 24, 94, 72, 18,  8, 46, 29, 32, 40, 62, 76, 36],
    [20, 69, 36, 41, 72, 30, 23, 88, 34, 62, 99, 69, 82, 67, 59, 85, 74,  4, 36, 16],
    [20, 73, 35, 29, 78, 31, 90,  1, 74, 31, 49, 71, 48, 86, 81, 16, 23, 57,  5, 54],
    [ 1, 70, 54, 71, 83, 51, 54, 69, 16, 92, 33, 48, 61, 43, 52,  1, 89, 19, 67, 48]
]

L(n) 2..5
   maxproduct(MATRIX, n)

Output:

The max 2-product is 9215, product of [95, 97] at row [7, 9], col [8].
The max 3-product is 776776, product of [91, 88, 97] at row [7, 10], col [15].
The max 4-product is 51267216, product of [66, 91, 88, 97] at row [6, 10], col [15].
The max 5-product is 2326829868, product of [62, 99, 69, 82, 67] at row [17], col [9, 14].

ALGOL 68

BEGIN # find the maximum product of 4 adjacent numbers in a row or column of a matrix #
    [,]INT m = ( ( 08, 02, 22, 97, 38, 15, 00, 40, 00, 75, 04, 05, 07, 78, 52, 12, 50, 77, 91, 08 )
               , ( 49, 49, 99, 40, 17, 81, 18, 57, 60, 87, 17, 40, 98, 43, 69, 48, 04, 56, 62, 00 )
               , ( 81, 49, 31, 73, 55, 79, 14, 29, 93, 71, 40, 67, 53, 88, 30, 03, 49, 13, 36, 65 )
               , ( 52, 70, 95, 23, 04, 60, 11, 42, 69, 24, 68, 56, 01, 32, 56, 71, 37, 02, 36, 91 )
               , ( 22, 31, 16, 71, 51, 67, 63, 89, 41, 92, 36, 54, 22, 40, 40, 28, 66, 33, 13, 80 )
               , ( 24, 47, 32, 60, 99, 03, 45, 02, 44, 75, 33, 53, 78, 36, 84, 20, 35, 17, 12, 50 )
               , ( 32, 98, 81, 28, 64, 23, 67, 10, 26, 38, 40, 67, 59, 54, 70, 66, 18, 38, 64, 70 )
               , ( 67, 26, 20, 68, 02, 62, 12, 20, 95, 63, 94, 39, 63, 08, 40, 91, 66, 49, 94, 21 )
               , ( 24, 55, 58, 05, 66, 73, 99, 26, 97, 17, 78, 78, 96, 83, 14, 88, 34, 89, 63, 72 )
               , ( 21, 36, 23, 09, 75, 00, 76, 44, 20, 45, 35, 14, 00, 61, 33, 97, 34, 31, 33, 95 )
               , ( 78, 17, 53, 28, 22, 75, 31, 67, 15, 94, 03, 80, 04, 62, 16, 14, 09, 53, 56, 92 )
               , ( 16, 39, 05, 42, 96, 35, 31, 47, 55, 58, 88, 24, 00, 17, 54, 24, 36, 29, 85, 57 )
               , ( 86, 56, 00, 48, 35, 71, 89, 07, 05, 44, 44, 37, 44, 60, 21, 58, 51, 54, 17, 58 )
               , ( 19, 80, 81, 68, 05, 94, 47, 69, 28, 73, 92, 13, 86, 52, 17, 77, 04, 89, 55, 40 )
               , ( 04, 52, 08, 83, 97, 35, 99, 16, 07, 97, 57, 32, 16, 26, 26, 79, 33, 27, 98, 66 )
               , ( 88, 36, 68, 87, 57, 62, 20, 72, 03, 46, 33, 67, 46, 55, 12, 32, 63, 93, 53, 69 )
               , ( 04, 42, 16, 73, 38, 25, 39, 11, 24, 94, 72, 18, 08, 46, 29, 32, 40, 62, 76, 36 )
               , ( 20, 69, 36, 41, 72, 30, 23, 88, 34, 62, 99, 69, 82, 67, 59, 85, 74, 04, 36, 16 )
               , ( 20, 73, 35, 29, 78, 31, 90, 01, 74, 31, 49, 71, 48, 86, 81, 16, 23, 57, 05, 54 )
               , ( 01, 70, 54, 71, 83, 51, 54, 69, 16, 92, 33, 48, 61, 43, 52, 01, 89, 19, 67, 48 )
               );
    INT elements     = 4; # number of elements to multiply #
    INT max product := - max int; # most negative integer #
    INT  row := 0, col := 0;
    BOOL horizontal := TRUE;
    FOR i FROM 1 LWB m TO 1 UPB m DO
        FOR j FROM 2 LWB m TO ( 2 UPB m - elements ) + 1 DO
            INT ij product := m[ i, j ] * m[ i, j + 1 ] * m[ i, j + 2 ] * m[ i, j + 3 ];
            IF  ij product > max product THEN
                max product := ij product;
                row         := i;
                col         := j
            FI
        OD
    OD; 
    FOR j FROM 2 LWB m TO 2 UPB m DO
        FOR i FROM 1 LWB m TO ( 2 UPB m - elements ) + 1 DO
            INT ij product := m[ i, j ] * m[ i + 1, j ] * m[ i + 2, j ] * m[ i + 3, j ];
            IF  ij product > max product THEN
                max product := ij product;
                row         := i;
                col         := j;
                horizontal  := FALSE
            FI
        OD
    OD;
    print( ( "The maximum product of ", whole( elements, 0 )
           , " elements: ", whole( max product, 0 )
           , " is the ", IF horizontal THEN "row" ELSE "column" FI
           , " of ", whole( elements, 0 )
           , " numbers starting at: ", whole( row, 0 ), ", ", whole( col, 0 )
           )
         )
END

Output:

The maximum product of 4 elements: 51267216 is the column of 4 numbers starting at: 7, 16

Arturo

grid: [
    [08 02 22 97 38 15 00 40 00 75 04 05 07 78 52 12 50 77 91 08]
    [49 49 99 40 17 81 18 57 60 87 17 40 98 43 69 48 04 56 62 00]
    [81 49 31 73 55 79 14 29 93 71 40 67 53 88 30 03 49 13 36 65]
    [52 70 95 23 04 60 11 42 69 24 68 56 01 32 56 71 37 02 36 91]
    [22 31 16 71 51 67 63 89 41 92 36 54 22 40 40 28 66 33 13 80]
    [24 47 32 60 99 03 45 02 44 75 33 53 78 36 84 20 35 17 12 50]
    [32 98 81 28 64 23 67 10 26 38 40 67 59 54 70 66 18 38 64 70]
    [67 26 20 68 02 62 12 20 95 63 94 39 63 08 40 91 66 49 94 21]
    [24 55 58 05 66 73 99 26 97 17 78 78 96 83 14 88 34 89 63 72]
    [21 36 23 09 75 00 76 44 20 45 35 14 00 61 33 97 34 31 33 95]
    [78 17 53 28 22 75 31 67 15 94 03 80 04 62 16 14 09 53 56 92]
    [16 39 05 42 96 35 31 47 55 58 88 24 00 17 54 24 36 29 85 57]
    [86 56 00 48 35 71 89 07 05 44 44 37 44 60 21 58 51 54 17 58]
    [19 80 81 68 05 94 47 69 28 73 92 13 86 52 17 77 04 89 55 40]
    [04 52 08 83 97 35 99 16 07 97 57 32 16 26 26 79 33 27 98 66]
    [88 36 68 87 57 62 20 72 03 46 33 67 46 55 12 32 63 93 53 69]
    [04 42 16 73 38 25 39 11 24 94 72 18 08 46 29 32 40 62 76 36]
    [20 69 36 41 72 30 23 88 34 62 99 69 82 67 59 85 74 04 36 16]
    [20 73 35 29 78 31 90 01 74 31 49 71 48 86 81 16 23 57 05 54]
    [01 70 54 71 83 51 54 69 16 92 33 48 61 43 52 01 89 19 67 48]
]

findLargestProduct: function [g][
    dim: size g
    maxProd: [[], 0]
    loop 0..dec dim 'row [
        loop 0..dim-4 'col [
            items: @[g\[row]\[col], g\[row]\[col+1], g\[row]\[col+2], g\[row]\[col+3]]
            prod: product items
            if prod > last maxProd [
                maxProd: @[items, prod]
            ]
        ]
    ]
    loop 0..dec dim 'col [
        loop 0..dim-4 'row [
            items: @[g\[row]\[col], g\[row+1]\[col], g\[row+2]\[col], g\[row+3]\[col]]
            prod: product items
            if prod > last maxProd [
                maxProd: @[items, prod]
            ]
        ]
    ]
    return maxProd
]

print findLargestProduct grid

Output:

[66 91 88 97] 51267216

AutoHotkey

Grid = 
(
08 02 22 97 38 15 00 40 00 75 04 05 07 78 52 12 50 77 91 08
49 49 99 40 17 81 18 57 60 87 17 40 98 43 69 48 04 56 62 00
81 49 31 73 55 79 14 29 93 71 40 67 53 88 30 03 49 13 36 65
52 70 95 23 04 60 11 42 69 24 68 56 01 32 56 71 37 02 36 91
22 31 16 71 51 67 63 89 41 92 36 54 22 40 40 28 66 33 13 80
24 47 32 60 99 03 45 02 44 75 33 53 78 36 84 20 35 17 12 50
32 98 81 28 64 23 67 10 26 38 40 67 59 54 70 66 18 38 64 70
67 26 20 68 02 62 12 20 95 63 94 39 63 08 40 91 66 49 94 21
24 55 58 05 66 73 99 26 97 17 78 78 96 83 14 88 34 89 63 72
21 36 23 09 75 00 76 44 20 45 35 14 00 61 33 97 34 31 33 95
78 17 53 28 22 75 31 67 15 94 03 80 04 62 16 14 09 53 56 92
16 39 05 42 96 35 31 47 55 58 88 24 00 17 54 24 36 29 85 57
86 56 00 48 35 71 89 07 05 44 44 37 44 60 21 58 51 54 17 58
19 80 81 68 05 94 47 69 28 73 92 13 86 52 17 77 04 89 55 40
04 52 08 83 97 35 99 16 07 97 57 32 16 26 26 79 33 27 98 66
88 36 68 87 57 62 20 72 03 46 33 67 46 55 12 32 63 93 53 69
04 42 16 73 38 25 39 11 24 94 72 18 08 46 29 32 40 62 76 36
20 69 36 41 72 30 23 88 34 62 99 69 82 67 59 85 74 04 36 16
20 73 35 29 78 31 90 01 74 31 49 71 48 86 81 16 23 57 05 54
01 70 54 71 83 51 54 69 16 92 33 48 61 43 52 01 89 19 67 48
)

oGrid := []
for r, line in StrSplit(grid, "`n", "`r")
    for c, v in StrSplit(line, " ")
        oGrid[r, c] := v

n := 4
Steps := []
for r, row in oGrid
{
    for c, v in row
    {
        prodR := prodC := 1
        strR := strC := ""
        loop % n
        {
            prodR *= oGrid[r, c + A_Index - 1]
            prodC *= oGrid[r + A_Index - 1, C]
            strR  .= oGrid[r, c + A_Index - 1] "*"
            strC  .= oGrid[r + A_Index - 1, C] "*"
        }
        Steps[prodR] .= "`n" Trim(strR, "*") " @ Row " r ", Col " c " - Col " c+n-1
        Steps[prodC] .= "`n" Trim(strC, "*") " @ Row " r " - Row " r+n-1 ", Col " c
        maxProd := maxProd > prodR ? maxProd : prodR
        maxProd := maxProd > prodC ? maxProd : prodC
    }
}
MsgBox, 262144, ,% result := "Max Product = " maxProd . Steps[maxProd]

Output:

Max Product = 51267216
66*91*88*97 @ Row 7 - Row 10, Col 16

AWK

# syntax: GAWK -f LARGEST_PRODUCT_IN_A_GRID.AWK
BEGIN {
    grid[++row] = "08,02,22,97,38,15,00,40,00,75,04,05,07,78,52,12,50,77,91,08"
    grid[++row] = "49,49,99,40,17,81,18,57,60,87,17,40,98,43,69,48,04,56,62,00"
    grid[++row] = "81,49,31,73,55,79,14,29,93,71,40,67,53,88,30,03,49,13,36,65"
    grid[++row] = "52,70,95,23,04,60,11,42,69,24,68,56,01,32,56,71,37,02,36,91"
    grid[++row] = "22,31,16,71,51,67,63,89,41,92,36,54,22,40,40,28,66,33,13,80"
    grid[++row] = "24,47,32,60,99,03,45,02,44,75,33,53,78,36,84,20,35,17,12,50"
    grid[++row] = "32,98,81,28,64,23,67,10,26,38,40,67,59,54,70,66,18,38,64,70"
    grid[++row] = "67,26,20,68,02,62,12,20,95,63,94,39,63,08,40,91,66,49,94,21"
    grid[++row] = "24,55,58,05,66,73,99,26,97,17,78,78,96,83,14,88,34,89,63,72"
    grid[++row] = "21,36,23,09,75,00,76,44,20,45,35,14,00,61,33,97,34,31,33,95"
    grid[++row] = "78,17,53,28,22,75,31,67,15,94,03,80,04,62,16,14,09,53,56,92"
    grid[++row] = "16,39,05,42,96,35,31,47,55,58,88,24,00,17,54,24,36,29,85,57"
    grid[++row] = "86,56,00,48,35,71,89,07,05,44,44,37,44,60,21,58,51,54,17,58"
    grid[++row] = "19,80,81,68,05,94,47,69,28,73,92,13,86,52,17,77,04,89,55,40"
    grid[++row] = "04,52,08,83,97,35,99,16,07,97,57,32,16,26,26,79,33,27,98,66"
    grid[++row] = "88,36,68,87,57,62,20,72,03,46,33,67,46,55,12,32,63,93,53,69"
    grid[++row] = "04,42,16,73,38,25,39,11,24,94,72,18,08,46,29,32,40,62,76,36"
    grid[++row] = "20,69,36,41,72,30,23,88,34,62,99,69,82,67,59,85,74,04,36,16"
    grid[++row] = "20,73,35,29,78,31,90,01,74,31,49,71,48,86,81,16,23,57,05,54"
    grid[++row] = "01,70,54,71,83,51,54,69,16,92,33,48,61,43,52,01,89,19,67,48"
    for (r=1; r<=row; r++) { # build 2-dimensional array
      col = split(grid[r],tmp_arr,",")
      width_arr[col] = ""
      for (c=1; c<=col; c++) {
        arr[r][c] = tmp_arr[c]
      }
    }
    if (length(width_arr) != 1) {
      print("error: arrays must be same length")
      exit(1)
    }
    delete grid
    delete tmp_arr
    delete width_arr
    for (r=1; r<=row-3; r++) { # top-bottom / down
      for (c=1; c<=col; c++) {
        product = (p0=arr[r][c]) * (p1=arr[r+1][c]) * (p2=arr[r+2][c]) * (p3=arr[r+3][c])
        if (product > ans) {
          ans = product
          cell_info = sprintf("%d*%d*%d*%d in column %d rows %d-%d",p0,p1,p2,p3,c,r,r+3)
        }
      }
    }
    for (c=1; c<=col-3; c++) { # left-right / across
      for (r=1; r<=row; r++) {
        product = (p0=arr[r][c]) * (p1=arr[r][c+1]) * (p2=arr[r][c+2]) * (p3=arr[r][c+3])
        if (product > ans) {
          ans = product
          cell_info = sprintf("%d*%d*%d*%d in row %d columns %d-%d",p0,p1,p2,p3,r,c,c+3)
        }
      }
    }
    printf("%d = %s\n",ans,cell_info)
    exit(0)
}

Output:

51267216 = 66*91*88*97 in column 16 rows 7-10

BASIC

ANSI BASIC

Translation of: FreeBASIC

Works with: Decimal BASIC

100 REM Largest product in a grid
110 DATA 08, 02, 22, 97, 38, 15, 00, 40, 00, 75, 04, 05, 07, 78, 52, 12, 50, 77, 91, 08
120 DATA 49, 49, 99, 40, 17, 81, 18, 57, 60, 87, 17, 40, 98, 43, 69, 48, 04, 56, 62, 00
130 DATA 81, 49, 31, 73, 55, 79, 14, 29, 93, 71, 40, 67, 53, 88, 30, 03, 49, 13, 36, 65
140 DATA 52, 70, 95, 23, 04, 60, 11, 42, 69, 24, 68, 56, 01, 32, 56, 71, 37, 02, 36, 91
150 DATA 22, 31, 16, 71, 51, 67, 63, 89, 41, 92, 36, 54, 22, 40, 40, 28, 66, 33, 13, 80
160 DATA 24, 47, 32, 60, 99, 03, 45, 02, 44, 75, 33, 53, 78, 36, 84, 20, 35, 17, 12, 50
170 DATA 32, 98, 81, 28, 64, 23, 67, 10, 26, 38, 40, 67, 59, 54, 70, 66, 18, 38, 64, 70
180 DATA 67, 26, 20, 68, 02, 62, 12, 20, 95, 63, 94, 39, 63, 08, 40, 91, 66, 49, 94, 21
190 DATA 24, 55, 58, 05, 66, 73, 99, 26, 97, 17, 78, 78, 96, 83, 14, 88, 34, 89, 63, 72
200 DATA 21, 36, 23, 09, 75, 00, 76, 44, 20, 45, 35, 14, 00, 61, 33, 97, 34, 31, 33, 95
210 DATA 78, 17, 53, 28, 22, 75, 31, 67, 15, 94, 03, 80, 04, 62, 16, 14, 09, 53, 56, 92
220 DATA 16, 39, 05, 42, 96, 35, 31, 47, 55, 58, 88, 24, 00, 17, 54, 24, 36, 29, 85, 57
230 DATA 86, 56, 00, 48, 35, 71, 89, 07, 05, 44, 44, 37, 44, 60, 21, 58, 51, 54, 17, 58
240 DATA 19, 80, 81, 68, 05, 94, 47, 69, 28, 73, 92, 13, 86, 52, 17, 77, 04, 89, 55, 40
250 DATA 04, 52, 08, 83, 97, 35, 99, 16, 07, 97, 57, 32, 16, 26, 26, 79, 33, 27, 98, 66
260 DATA 88, 36, 68, 87, 57, 62, 20, 72, 03, 46, 33, 67, 46, 55, 12, 32, 63, 93, 53, 69
270 DATA 04, 42, 16, 73, 38, 25, 39, 11, 24, 94, 72, 18, 08, 46, 29, 32, 40, 62, 76, 36
280 DATA 20, 69, 36, 41, 72, 30, 23, 88, 34, 62, 99, 69, 82, 67, 59, 85, 74, 04, 36, 16
290 DATA 20, 73, 35, 29, 78, 31, 90, 01, 74, 31, 49, 71, 48, 86, 81, 16, 23, 57, 05, 54
300 DATA 01, 70, 54, 71, 83, 51, 54, 69, 16, 92, 33, 48, 61, 43, 52, 01, 89, 19, 67, 48
310 REM 
320 DIM Grid(1 TO 20, 1 TO 20)
330 LET Champ = 0
340 LET Across = 0
350 FOR Row = 1 TO 20
360    FOR Col = 1 TO 20
370       READ Grid(Row, Col)
380    NEXT Col
390 NEXT Row
400 REM ** Search down
410 FOR Row = 1 TO 17
420    FOR Col = 1 TO 20
430       LET Prod = Grid(Row, Col) * Grid(Row + 1, Col) * Grid(Row + 2, Col) * Grid(Row + 3, Col)
440       IF Prod > Champ THEN
450          LET CR = Row
460          LET CC = Col
470          LET Champ = Prod
480       end IF
490    NEXT Col
500 NEXT Row
510 REM ** Search across
520 FOR Row = 1 TO 20
530    FOR Col = 1 TO 17
540       LET Prod = Grid(Row, Col) * Grid(Row, Col + 1) * Grid(Row, Col + 2) * Grid(Row, Col + 3)
550       IF Prod > Champ THEN
560          LET CR = Row
570          LET CC = Col
580          LET Champ = Prod
590          LET Across = 1
600       END IF
610    NEXT Col
620 NEXT Row
630 REM **
640 PRINT "The largest product was"; Champ; "at row"; CR; "and column"; CC; "(reading ";
650 IF Across = 0 THEN PRINT "down)." ELSE PRINT "across)."
660 END

Output:

The largest product was 51267216 at row 7 and column 16 (reading down).

FreeBASIC

data 08,02,22,97,38,15,00,40,00,75,04,05,07,78,52,12,50,77,91,08
data 49,49,99,40,17,81,18,57,60,87,17,40,98,43,69,48,04,56,62,00
data 81,49,31,73,55,79,14,29,93,71,40,67,53,88,30,03,49,13,36,65
data 52,70,95,23,04,60,11,42,69,24,68,56,01,32,56,71,37,02,36,91
data 22,31,16,71,51,67,63,89,41,92,36,54,22,40,40,28,66,33,13,80
data 24,47,32,60,99,03,45,02,44,75,33,53,78,36,84,20,35,17,12,50
data 32,98,81,28,64,23,67,10,26,38,40,67,59,54,70,66,18,38,64,70
data 67,26,20,68,02,62,12,20,95,63,94,39,63,08,40,91,66,49,94,21
data 24,55,58,05,66,73,99,26,97,17,78,78,96,83,14,88,34,89,63,72
data 21,36,23,09,75,00,76,44,20,45,35,14,00,61,33,97,34,31,33,95
data 78,17,53,28,22,75,31,67,15,94,03,80,04,62,16,14,09,53,56,92
data 16,39,05,42,96,35,31,47,55,58,88,24,00,17,54,24,36,29,85,57
data 86,56,00,48,35,71,89,07,05,44,44,37,44,60,21,58,51,54,17,58
data 19,80,81,68,05,94,47,69,28,73,92,13,86,52,17,77,04,89,55,40
data 04,52,08,83,97,35,99,16,07,97,57,32,16,26,26,79,33,27,98,66
data 88,36,68,87,57,62,20,72,03,46,33,67,46,55,12,32,63,93,53,69
data 04,42,16,73,38,25,39,11,24,94,72,18,08,46,29,32,40,62,76,36
data 20,69,36,41,72,30,23,88,34,62,99,69,82,67,59,85,74,04,36,16
data 20,73,35,29,78,31,90,01,74,31,49,71,48,86,81,16,23,57,05,54
data 01,70,54,71,83,51,54,69,16,92,33,48,61,43,52,01,89,19,67,48

dim as integer grid(1 to 20, 1 to 20), row, col, prod
dim as integer champ = 0, cr, cc
dim as boolean across = false
for row = 1 to 20
    for col = 1 to 20
        read grid(row, col)
    next col
next row

'search down
for row = 1 to 17
    for col = 1 to 20
        prod = grid(row, col)*grid(row + 1, col)*grid(row + 2, col)*grid(row + 3, col)
        if prod > champ then
            cr = row
            cc = col
            champ = prod
        end if
    next col
next row

'search across
for row = 1 to 20
    for col = 1 to 17
        prod = grid(row, col)*grid(row, col + 1)*grid(row, col + 2)*grid(row, col + 3)
        if prod > champ then
            cr = row
            cc = col
            champ = prod
            across = true
        end if
    next col
next row

print "The largest product was ";champ;" at row ";cr;" and column ";cc;" (reading ";
if across then print "across)." else print "down)."

Output:

The largest product was  51267216 at row  7 and column  16 (reading down).

Minimal BASIC

Translation of: FreeBASIC

Works with: BASICA

10 REM Largest product in a grid
20 REM 2 lines of DATA fill 1 row
30 DATA 08, 02, 22, 97, 38, 15, 00, 40, 00, 75
40 DATA 04, 05, 07, 78, 52, 12, 50, 77, 91, 08
50 DATA 49, 49, 99, 40, 17, 81, 18, 57, 60, 87
60 DATA 17, 40, 98, 43, 69, 48, 04, 56, 62, 00
70 DATA 81, 49, 31, 73, 55, 79, 14, 29, 93, 71
80 DATA 40, 67, 53, 88, 30, 03, 49, 13, 36, 65
90 DATA 52, 70, 95, 23, 04, 60, 11, 42, 69, 24
100 DATA 68, 56, 01, 32, 56, 71, 37, 02, 36, 91
110 DATA 22, 31, 16, 71, 51, 67, 63, 89, 41, 92
120 DATA 36, 54, 22, 40, 40, 28, 66, 33, 13, 80
130 DATA 24, 47, 32, 60, 99, 03, 45, 02, 44, 75
140 DATA 33, 53, 78, 36, 84, 20, 35, 17, 12, 50
150 DATA 32, 98, 81, 28, 64, 23, 67, 10, 26, 38
160 DATA 40, 67, 59, 54, 70, 66, 18, 38, 64, 70
170 DATA 67, 26, 20, 68, 02, 62, 12, 20, 95, 63
180 DATA 94, 39, 63, 08, 40, 91, 66, 49, 94, 21
190 DATA 24, 55, 58, 05, 66, 73, 99, 26, 97, 17
200 DATA 78, 78, 96, 83, 14, 88, 34, 89, 63, 72
210 DATA 21, 36, 23, 09, 75, 00, 76, 44, 20, 45
220 DATA 35, 14, 00, 61, 33, 97, 34, 31, 33, 95
230 DATA 78, 17, 53, 28, 22, 75, 31, 67, 15, 94
240 DATA 03, 80, 04, 62, 16, 14, 09, 53, 56, 92
250 DATA 16, 39, 05, 42, 96, 35, 31, 47, 55, 58
260 DATA 88, 24, 00, 17, 54, 24, 36, 29, 85, 57
270 DATA 86, 56, 00, 48, 35, 71, 89, 07, 05, 44
280 DATA 44, 37, 44, 60, 21, 58, 51, 54, 17, 58
290 DATA 19, 80, 81, 68, 05, 94, 47, 69, 28, 73
300 DATA 92, 13, 86, 52, 17, 77, 04, 89, 55, 40
310 DATA 04, 52, 08, 83, 97, 35, 99, 16, 07, 97
320 DATA 57, 32, 16, 26, 26, 79, 33, 27, 98, 66
330 DATA 88, 36, 68, 87, 57, 62, 20, 72, 03, 46
340 DATA 33, 67, 46, 55, 12, 32, 63, 93, 53, 69
350 DATA 04, 42, 16, 73, 38, 25, 39, 11, 24, 94
360 DATA 72, 18, 08, 46, 29, 32, 40, 62, 76, 36
370 DATA 20, 69, 36, 41, 72, 30, 23, 88, 34, 62
380 DATA 99, 69, 82, 67, 59, 85, 74, 04, 36, 16
390 DATA 20, 73, 35, 29, 78, 31, 90, 01, 74, 31
400 DATA 49, 71, 48, 86, 81, 16, 23, 57, 05, 54
410 DATA 01, 70, 54, 71, 83, 51, 54, 69, 16, 92
420 DATA 33, 48, 61, 43, 52, 01, 89, 19, 67, 48
430 REM
440 OPTION BASE 1
450 DIM G(20,20)
460 LET X = 0
470 LET A = 0
480 FOR R = 1 TO 20
490 FOR C = 1 TO 20
500 READ G(R,C)
510 NEXT C
520 NEXT R
530 REM ** Search down
540 FOR R = 1 TO 17
550 FOR C = 1 TO 20
560 LET P = G(R,C)*G(R+1,C)*G(R+2,C)*G(R+3,C)
570 IF P <= X THEN 610
580 LET R0 = R
590 LET C0 = C
600 LET X = P
610 NEXT C
620 NEXT R
630 REM ** Search across
640 FOR R = 1 TO 20
650 FOR C = 1 TO 17
660 LET P = G(R,C)*G(R,C+1)*G(R,C+2)*G(R,C+3)
670 IF P <= X THEN 720
680 LET R0 = R
690 LET C0 = C
700 LET X = P
710 LET A = 1
720 NEXT C
730 NEXT R
740 REM **
750 PRINT "The largest product was"; X 
760 PRINT "at row"; R0; "and column"; C0 
770 IF A = 0 THEN 800
780 PRINT "(reading across)." 
790 GOTO 810 
800 PRINT "(reading down)."
810 END

Output:

The largest product was 5.126722E+07
at row 7 and column 16 
(reading down).

C

/* Largest product in a grid */
#include<stdio.h>
#define PROD_LEN 4
#define GRID_SIZE 20

int main()
{
  long int max, prod;
  int i, j, k, k_max, j_max = GRID_SIZE - PROD_LEN;
  int grid[GRID_SIZE][GRID_SIZE] = 
  {
    { 8,  2, 22, 97, 38, 15,  0, 40,  0, 75,  4,  5,  7, 78, 52, 12, 50, 77, 91,  8}, 
    {49, 49, 99, 40, 17, 81, 18, 57, 60, 87, 17, 40, 98, 43, 69, 48,  4, 56, 62,  0}, 
    {81, 49, 31, 73, 55, 79, 14, 29, 93, 71, 40, 67, 53, 88, 30,  3, 49, 13, 36, 65}, 
    {52, 70, 95, 23,  4, 60, 11, 42, 69, 24, 68, 56,  1, 32, 56, 71, 37,  2, 36, 91}, 
    {22, 31, 16, 71, 51, 67, 63, 89, 41, 92, 36, 54, 22, 40, 40, 28, 66, 33, 13, 80}, 
    {24, 47, 32, 60, 99,  3, 45,  2, 44, 75, 33, 53, 78, 36, 84, 20, 35, 17, 12, 50}, 
    {32, 98, 81, 28, 64, 23, 67, 10, 26, 38, 40, 67, 59, 54, 70, 66, 18, 38, 64, 70}, 
    {67, 26, 20, 68,  2, 62, 12, 20, 95, 63, 94, 39, 63,  8, 40, 91, 66, 49, 94, 21}, 
    {24, 55, 58,  5, 66, 73, 99, 26, 97, 17, 78, 78, 96, 83, 14, 88, 34, 89, 63, 72}, 
    {21, 36, 23,  9, 75,  0, 76, 44, 20, 45, 35, 14,  0, 61, 33, 97, 34, 31, 33, 95}, 
    {78, 17, 53, 28, 22, 75, 31, 67, 15, 94,  3, 80,  4, 62, 16, 14,  9, 53, 56, 92}, 
    {16, 39,  5, 42, 96, 35, 31, 47, 55, 58, 88, 24,  0, 17, 54, 24, 36, 29, 85, 57}, 
    {86, 56,  0, 48, 35, 71, 89,  7,  5, 44, 44, 37, 44, 60, 21, 58, 51, 54, 17, 58}, 
    {19, 80, 81, 68,  5, 94, 47, 69, 28, 73, 92, 13, 86, 52, 17, 77,  4, 89, 55, 40}, 
    { 4, 52,  8, 83, 97, 35, 99, 16,  7, 97, 57, 32, 16, 26, 26, 79, 33, 27, 98, 66}, 
    {88, 36, 68, 87, 57, 62, 20, 72,  3, 46, 33, 67, 46, 55, 12, 32, 63, 93, 53, 69}, 
    { 4, 42, 16, 73, 38, 25, 39, 11, 24, 94, 72, 18,  8, 46, 29, 32, 40, 62, 76, 36}, 
    {20, 69, 36, 41, 72, 30, 23, 88, 34, 62, 99, 69, 82, 67, 59, 85, 74,  4, 36, 16}, 
    {20, 73, 35, 29, 78, 31, 90,  1, 74, 31, 49, 71, 48, 86, 81, 16, 23, 57,  5, 54}, 
    { 1, 70, 54, 71, 83, 51, 54, 69, 16, 92, 33, 48, 61, 43, 52,  1, 89, 19, 67, 48}
  };
  max = 0;
  for (j = 0; j < GRID_SIZE; j++)
    for (i = 0; i <= j_max; i++)
      for (k = i, prod = 1, k_max = PROD_LEN + i - 1; k <= k_max; k++)
      { 
        prod *= grid[j][k];
        if (prod > max) 
          max = prod;
      }
  for (j = 0; j <= j_max; j++)
    for (i = 0; i < GRID_SIZE; i++)
      for (k = j, prod = 1, k_max = PROD_LEN + j - 1; k <= k_max; k++)
      { 
        prod *= grid[k][i];
        if (prod > max) 
          max = prod;
      }
  printf("%d\n", max);
}

Output:

51267216

C#

Translation of: C

// Largest product in a grid
using System;

class Program
{
  const int prodLen = 4;
  const int gridSize = 20;

  public static void Main()
  {
    int jMax = gridSize - prodLen;
    int[ , ] grid = new int[gridSize, gridSize]
    {
      { 8,  2, 22, 97, 38, 15,  0, 40,  0, 75,  4,  5,  7, 78, 52, 12, 50, 77, 91,  8}, 
      {49, 49, 99, 40, 17, 81, 18, 57, 60, 87, 17, 40, 98, 43, 69, 48,  4, 56, 62,  0}, 
      {81, 49, 31, 73, 55, 79, 14, 29, 93, 71, 40, 67, 53, 88, 30,  3, 49, 13, 36, 65}, 
      {52, 70, 95, 23,  4, 60, 11, 42, 69, 24, 68, 56,  1, 32, 56, 71, 37,  2, 36, 91}, 
      {22, 31, 16, 71, 51, 67, 63, 89, 41, 92, 36, 54, 22, 40, 40, 28, 66, 33, 13, 80}, 
      {24, 47, 32, 60, 99,  3, 45,  2, 44, 75, 33, 53, 78, 36, 84, 20, 35, 17, 12, 50}, 
      {32, 98, 81, 28, 64, 23, 67, 10, 26, 38, 40, 67, 59, 54, 70, 66, 18, 38, 64, 70}, 
      {67, 26, 20, 68,  2, 62, 12, 20, 95, 63, 94, 39, 63,  8, 40, 91, 66, 49, 94, 21}, 
      {24, 55, 58,  5, 66, 73, 99, 26, 97, 17, 78, 78, 96, 83, 14, 88, 34, 89, 63, 72}, 
      {21, 36, 23,  9, 75,  0, 76, 44, 20, 45, 35, 14,  0, 61, 33, 97, 34, 31, 33, 95}, 
      {78, 17, 53, 28, 22, 75, 31, 67, 15, 94,  3, 80,  4, 62, 16, 14,  9, 53, 56, 92}, 
      {16, 39,  5, 42, 96, 35, 31, 47, 55, 58, 88, 24,  0, 17, 54, 24, 36, 29, 85, 57}, 
      {86, 56,  0, 48, 35, 71, 89,  7,  5, 44, 44, 37, 44, 60, 21, 58, 51, 54, 17, 58}, 
      {19, 80, 81, 68,  5, 94, 47, 69, 28, 73, 92, 13, 86, 52, 17, 77,  4, 89, 55, 40}, 
      { 4, 52,  8, 83, 97, 35, 99, 16,  7, 97, 57, 32, 16, 26, 26, 79, 33, 27, 98, 66}, 
      {88, 36, 68, 87, 57, 62, 20, 72,  3, 46, 33, 67, 46, 55, 12, 32, 63, 93, 53, 69}, 
      { 4, 42, 16, 73, 38, 25, 39, 11, 24, 94, 72, 18,  8, 46, 29, 32, 40, 62, 76, 36}, 
      {20, 69, 36, 41, 72, 30, 23, 88, 34, 62, 99, 69, 82, 67, 59, 85, 74,  4, 36, 16}, 
      {20, 73, 35, 29, 78, 31, 90,  1, 74, 31, 49, 71, 48, 86, 81, 16, 23, 57,  5, 54}, 
      { 1, 70, 54, 71, 83, 51, 54, 69, 16, 92, 33, 48, 61, 43, 52,  1, 89, 19, 67, 48}
    };
    long max = 0;
    for (int j = 0; j < gridSize; j++)
      for (int i = 0; i <= jMax; i++)
      {
        long prod = 1;
        for (int k = i, kMax = prodLen + i - 1; k <= kMax; k++)
        { 
          prod *= grid[j, k];
          if (prod > max) 
            max = prod;
        }
      }
    for (int j = 0; j <= jMax; j++)
      for (int i = 0; i < gridSize; i++)
      {
        long prod = 1;
        for (int k = j, kMax = prodLen + j - 1; k <= kMax; k++)
        { 
          prod *= grid[k, i];
          if (prod > max) 
            max = prod;
        }
      }
    Console.WriteLine(max);
  }
}

Output:

51267216

C++

#include <cstdint>
#include <iostream>
#include <string>
#include <vector>

struct Coordinate {
	uint32_t x;
	int32_t y;

	std::string to_string() {
		if ( y == -1 ) {
			return std::to_string(x);
		}
		return "(" + std::to_string(x) + ", " + std::to_string(y) + ")";
	}
};

template <typename T>
void print_vector(const std::vector<T>& vec) {
	std::cout << "[";
	for ( uint32_t i = 0; i < vec.size() - 1; ++i ) {
		std::cout << vec[i] << ", ";
	}
	std::cout << vec.back() << "]";
}

void max_product(const std::vector<std::vector<uint64_t>>& grid, const uint32_t& product_length) {
	const uint32_t row_count = grid.size();
	const uint32_t col_count = grid[0].size();

	uint64_t max_product = 0;
	Coordinate max_row(0, 0);
	Coordinate max_col(0, 0);
	std::vector<uint64_t> numbers{};

	for ( uint32_t row = 0; row < row_count; ++row ) {
		for ( uint32_t col = 0; col < col_count; ++col ) {
			const uint32_t row2 = row + product_length;
			const uint32_t col2 = col + product_length;

			if  ( row < row_count - product_length ) {
				uint64_t product = 1;
				for ( uint32_t r = row; r < row2; ++r ) {
					product *= grid[r][col];
				}
				if ( product > max_product ) {
					max_product = product;
					max_row = Coordinate(row, row2);
					max_col = Coordinate(col, -1);
					numbers.clear();
					for ( uint32_t r = row; r < row2; ++r ) {
						numbers.emplace_back(grid[r][col]);
					}
				}
			}

			if ( col < col_count - product_length ) {
				uint64_t product = 1;
				for ( uint32_t c = col; c < col2; ++c ) {
				    product *= grid[row][c];
				}
				if ( product > max_product ) {
					max_product = product;
					max_row = Coordinate(row, -1);
					max_col = Coordinate(col, col2);
					numbers.clear();
					for ( uint32_t c = col; c < col2; ++c ) {
						numbers.emplace_back(grid[row][c]);
					}
				}
			}
		}
	}

	std::cout << "The maximum " << product_length << "-product is " << max_product << ", product of ";
		print_vector(numbers);
		std::cout << " at row " + max_row.to_string() << ", col " << max_col.to_string() << std::endl;
}

int main() {
	const std::vector<std::vector<uint64_t>> grid = {
		{  8,  2, 22, 97, 38, 15,  0, 40,  0, 75,  4,  5,  7, 78, 52, 12, 50, 77, 91,  8 },
		{ 49, 49, 99, 40, 17, 81, 18, 57, 60, 87, 17, 40, 98, 43, 69, 48,  4, 56, 62,  0 },
		{ 81, 49, 31, 73, 55, 79, 14, 29, 93, 71, 40, 67, 53, 88, 30,  3, 49, 13, 36, 65 },
		{ 52, 70, 95, 23,  4, 60, 11, 42, 69, 24, 68, 56,  1, 32, 56, 71, 37,  2, 36, 91 },
		{ 22, 31, 16, 71, 51, 67, 63, 89, 41, 92, 36, 54, 22, 40, 40, 28, 66, 33, 13, 80 },
		{ 24, 47, 32, 60, 99,  3, 45,  2, 44, 75, 33, 53, 78, 36, 84, 20, 35, 17, 12, 50 },
		{ 32, 98, 81, 28, 64, 23, 67, 10, 26, 38, 40, 67, 59, 54, 70, 66, 18, 38, 64, 70 },
		{ 67, 26, 20, 68,  2, 62, 12, 20, 95, 63, 94, 39, 63,  8, 40, 91, 66, 49, 94, 21 },
		{ 24, 55, 58,  5, 66, 73, 99, 26, 97, 17, 78, 78, 96, 83, 14, 88, 34, 89, 63, 72 },
		{ 21, 36, 23,  9, 75,  0, 76, 44, 20, 45, 35, 14,  0, 61, 33, 97, 34, 31, 33, 95 },
		{ 78, 17, 53, 28, 22, 75, 31, 67, 15, 94,  3, 80,  4, 62, 16, 14,  9, 53, 56, 92 },
		{ 16, 39,  5, 42, 96, 35, 31, 47, 55, 58, 88, 24,  0, 17, 54, 24, 36, 29, 85, 57 },
		{ 86, 56,  0, 48, 35, 71, 89,  7,  5, 44, 44, 37, 44, 60, 21, 58, 51, 54, 17, 58 },
		{ 19, 80, 81, 68,  5, 94, 47, 69, 28, 73, 92, 13, 86, 52, 17, 77,  4, 89, 55, 40 },
		{  4, 52,  8, 83, 97, 35, 99, 16,  7, 97, 57, 32, 16, 26, 26, 79, 33, 27, 98, 66 },
		{ 88, 36, 68, 87, 57, 62, 20, 72,  3, 46, 33, 67, 46, 55, 12, 32, 63, 93, 53, 69 },
		{  4, 42, 16, 73, 38, 25, 39, 11, 24, 94, 72, 18,  8, 46, 29, 32, 40, 62, 76, 36 },
		{ 20, 69, 36, 41, 72, 30, 23, 88, 34, 62, 99, 69, 82, 67, 59, 85, 74,  4, 36, 16 },
		{ 20, 73, 35, 29, 78, 31, 90,  1, 74, 31, 49, 71, 48, 86, 81, 16, 23, 57,  5, 54 },
		{  1, 70, 54, 71, 83, 51, 54, 69, 16, 92, 33, 48, 61, 43, 52,  1, 89, 19, 67, 48 }
	};

	for ( uint32_t n = 2; n <= 5; ++n ) {
	    max_product(grid, n);
	}
}

Output:

The maximum 2-product is 9215, product of [95, 97] at row (7, 9), col 8
The maximum 3-product is 776776, product of [91, 88, 97] at row (7, 10), col 15
The maximum 4-product is 51267216, product of [66, 91, 88, 97] at row (6, 10), col 15
The maximum 5-product is 2326829868, product of [62, 99, 69, 82, 67] at row 17, col (9, 14)

Delphi

Works with: Delphi version 6.0

Library: SysUtils,StdCtrls

type T2DGrid = array [0..19,0..19] of integer;


const PGrid: T2DGrid =(
(08,02,22,97,38,15,00,40,00,75,04,05,07,78,52,12,50,77,91,08),
(49,49,99,40,17,81,18,57,60,87,17,40,98,43,69,48,04,56,62,00),
(81,49,31,73,55,79,14,29,93,71,40,67,53,88,30,03,49,13,36,65),
(52,70,95,23,04,60,11,42,69,24,68,56,01,32,56,71,37,02,36,91),
(22,31,16,71,51,67,63,89,41,92,36,54,22,40,40,28,66,33,13,80),
(24,47,32,60,99,03,45,02,44,75,33,53,78,36,84,20,35,17,12,50),
(32,98,81,28,64,23,67,10,26,38,40,67,59,54,70,66,18,38,64,70),
(67,26,20,68,02,62,12,20,95,63,94,39,63,08,40,91,66,49,94,21),
(24,55,58,05,66,73,99,26,97,17,78,78,96,83,14,88,34,89,63,72),
(21,36,23,09,75,00,76,44,20,45,35,14,00,61,33,97,34,31,33,95),
(78,17,53,28,22,75,31,67,15,94,03,80,04,62,16,14,09,53,56,92),
(16,39,05,42,96,35,31,47,55,58,88,24,00,17,54,24,36,29,85,57),
(86,56,00,48,35,71,89,07,05,44,44,37,44,60,21,58,51,54,17,58),
(19,80,81,68,05,94,47,69,28,73,92,13,86,52,17,77,04,89,55,40),
(04,52,08,83,97,35,99,16,07,97,57,32,16,26,26,79,33,27,98,66),
(88,36,68,87,57,62,20,72,03,46,33,67,46,55,12,32,63,93,53,69),
(04,42,16,73,38,25,39,11,24,94,72,18,08,46,29,32,40,62,76,36),
(20,69,36,41,72,30,23,88,34,62,99,69,82,67,59,85,74,04,36,16),
(20,73,35,29,78,31,90,01,74,31,49,71,48,86,81,16,23,57,05,54),
(01,70,54,71,83,51,54,69,16,92,33,48,61,43,52,01,89,19,67,48));



function GetAdjacentProduct(Grid: T2DGrid; P: TPoint): integer;
{Get adjacent products from Point P}
var X,Y,Best1,Best2: integer;
var P2: TPoint;
begin
{Get the value at the target point}
Best1:=Grid[P.X,P.Y];
Best2:=Grid[P.X,P.Y];
{Multiply by next 3 elements to the right}
for X:=1 to 3 do
 if (P.X+X)<High(Grid) then
  Best1:=Best1 * Grid[P.X+X,P.Y];
{Multiply by next 3 elements down}
for Y:=1 to 3 do
 if (P.Y+Y)<High(Grid) then
  Best2:=Best2 * Grid[P.X,P.Y+Y];
{Return the best one}
if Best1>Best2 then Result:=Best1
else Result:=Best2;
end;


function GetBestGridProduct(Grid: T2DGrid): integer;
{Look at all positions in the grid and find largest product}
var P: integer;
var X,Y: integer;
begin
Result:=0;
for Y:=0 to High(Grid) do
for X:=0 to High(Grid[0]) do
	begin
	P:=GetAdjacentProduct(Grid,Point(X,Y));
	if P>Result then Result:=P;
	end;
end;

procedure TestGridProduct(Memo: TMemo);
{Run test problem}
var Best: integer;
begin
Best:=GetBestGridProduct(PGrid);
Memo.Lines.Add(IntToStr(Best));
end;

Output:

51267216

EasyLang

repeat
   s$ = input
   until s$ = ""
   m[][] &= number strsplit s$ " "
.
for i to 20
   for j to 16
      p = 1
      p2 = 1
      for k to 4
         p *= m[i][j + k]
         p2 *= m[j + k][i]
      .
      max = higher max p
      max = higher max p2
   .
.
print max
# 
input_data
08 02 22 97 38 15 00 40 00 75 04 05 07 78 52 12 50 77 91 08
49 49 99 40 17 81 18 57 60 87 17 40 98 43 69 48 04 56 62 00
81 49 31 73 55 79 14 29 93 71 40 67 53 88 30 03 49 13 36 65
52 70 95 23 04 60 11 42 69 24 68 56 01 32 56 71 37 02 36 91
22 31 16 71 51 67 63 89 41 92 36 54 22 40 40 28 66 33 13 80
24 47 32 60 99 03 45 02 44 75 33 53 78 36 84 20 35 17 12 50
32 98 81 28 64 23 67 10 26 38 40 67 59 54 70 66 18 38 64 70
67 26 20 68 02 62 12 20 95 63 94 39 63 08 40 91 66 49 94 21
24 55 58 05 66 73 99 26 97 17 78 78 96 83 14 88 34 89 63 72
21 36 23 09 75 00 76 44 20 45 35 14 00 61 33 97 34 31 33 95
78 17 53 28 22 75 31 67 15 94 03 80 04 62 16 14 09 53 56 92
16 39 05 42 96 35 31 47 55 58 88 24 00 17 54 24 36 29 85 57
86 56 00 48 35 71 89 07 05 44 44 37 44 60 21 58 51 54 17 58
19 80 81 68 05 94 47 69 28 73 92 13 86 52 17 77 04 89 55 40
04 52 08 83 97 35 99 16 07 97 57 32 16 26 26 79 33 27 98 66
88 36 68 87 57 62 20 72 03 46 33 67 46 55 12 32 63 93 53 69
04 42 16 73 38 25 39 11 24 94 72 18 08 46 29 32 40 62 76 36
20 69 36 41 72 30 23 88 34 62 99 69 82 67 59 85 74 04 36 16
20 73 35 29 78 31 90 01 74 31 49 71 48 86 81 16 23 57 05 54
01 70 54 71 83 51 54 69 16 92 33 48 61 43 52 01 89 19 67 48

Output:

51267216

F#

// Largest product in a grid. Nigel Galloway: December 30th., 2021
let N=[|8; 2;22;97;38;15; 0;40; 0;75; 4; 5; 7;78;52;12;50;77;91; 8;
       49;49;99;40;17;81;18;57;60;87;17;40;98;43;69;48; 4;56;62; 0;
       81;49;31;73;55;79;14;29;93;71;40;67;53;88;30; 3;49;13;36;65;
       52;70;95;23; 4;60;11;42;69;24;68;56; 1;32;56;71;37; 2;36;91;
       22;31;16;71;51;67;63;89;41;92;36;54;22;40;40;28;66;33;13;80;
       24;47;32;60;99; 3;45; 2;44;75;33;53;78;36;84;20;35;17;12;50;
       32;98;81;28;64;23;67;10;26;38;40;67;59;54;70;66;18;38;64;70;
       67;26;20;68; 2;62;12;20;95;63;94;39;63; 8;40;91;66;49;94;21;
       24;55;58; 5;66;73;99;26;97;17;78;78;96;83;14;88;34;89;63;72;
       21;36;23; 9;75; 0;76;44;20;45;35;14; 0;61;33;97;34;31;33;95;
       78;17;53;28;22;75;31;67;15;94; 3;80; 4;62;16;14; 9;53;56;92;
       16;39; 5;42;96;35;31;47;55;58;88;24; 0;17;54;24;36;29;85;57;
       86;56; 0;48;35;71;89; 7; 5;44;44;37;44;60;21;58;51;54;17;58;
       19;80;81;68; 5;94;47;69;28;73;92;13;86;52;17;77; 4;89;55;40;
        4;52; 8;83;97;35;99;16; 7;97;57;32;16;26;26;79;33;27;98;66;
       88;36;68;87;57;62;20;72; 3;46;33;67;46;55;12;32;63;93;53;69;
        4;42;16;73;38;25;39;11;24;94;72;18; 8;46;29;32;40;62;76;36;
       20;69;36;41;72;30;23;88;34;62;99;69;82;67;59;85;74; 4;36;16;
       20;73;35;29;78;31;90; 1;74;31;49;71;48;86;81;16;23;57; 5;54;
        1;70;54;71;83;51;54;69;16;92;33;48;61;43;52; 1;89;19;67;48|]

printfn "%d" (seq{for n in 0..19 do for g in 0..16 do let n=n*20 in yield N.[n+g]*N.[n+g+1]*N.[n+g+2]*N.[n+g+3]; for n in 0..19 do for g in 0..16 do let g=g*20 in yield N.[n+g]*N.[n+g+20]*N.[n+g+40]*N.[n+g+60]}|>Seq.max)

Output:

51267216

Factor

Works with: Factor version 0.99 2021-06-02

USING: grouping kernel math.matrices math.order prettyprint
sequences ;

: max-horizontal ( matrix m -- n )
    [ <clumps> ] curry map [ product ] matrix-map mmax ;

: max-product ( matrix m -- n )
    [ dup flip ] dip [ max-horizontal ] curry bi@ max ;

{
    08 02 22 97 38 15 00 40 00 75 04 05 07 78 52 12 50 77 91 08
    49 49 99 40 17 81 18 57 60 87 17 40 98 43 69 48 04 56 62 00
    81 49 31 73 55 79 14 29 93 71 40 67 53 88 30 03 49 13 36 65
    52 70 95 23 04 60 11 42 69 24 68 56 01 32 56 71 37 02 36 91
    22 31 16 71 51 67 63 89 41 92 36 54 22 40 40 28 66 33 13 80
    24 47 32 60 99 03 45 02 44 75 33 53 78 36 84 20 35 17 12 50
    32 98 81 28 64 23 67 10 26 38 40 67 59 54 70 66 18 38 64 70
    67 26 20 68 02 62 12 20 95 63 94 39 63 08 40 91 66 49 94 21
    24 55 58 05 66 73 99 26 97 17 78 78 96 83 14 88 34 89 63 72
    21 36 23 09 75 00 76 44 20 45 35 14 00 61 33 97 34 31 33 95
    78 17 53 28 22 75 31 67 15 94 03 80 04 62 16 14 09 53 56 92
    16 39 05 42 96 35 31 47 55 58 88 24 00 17 54 24 36 29 85 57
    86 56 00 48 35 71 89 07 05 44 44 37 44 60 21 58 51 54 17 58
    19 80 81 68 05 94 47 69 28 73 92 13 86 52 17 77 04 89 55 40
    04 52 08 83 97 35 99 16 07 97 57 32 16 26 26 79 33 27 98 66
    88 36 68 87 57 62 20 72 03 46 33 67 46 55 12 32 63 93 53 69
    04 42 16 73 38 25 39 11 24 94 72 18 08 46 29 32 40 62 76 36
    20 69 36 41 72 30 23 88 34 62 99 69 82 67 59 85 74 04 36 16
    20 73 35 29 78 31 90 01 74 31 49 71 48 86 81 16 23 57 05 54
    01 70 54 71 83 51 54 69 16 92 33 48 61 43 52 01 89 19 67 48
} 20 group

4 max-product .

Output:

51267216

Go

Translation of: Wren

Library: Go-rcu

package main

import (
    "fmt"
    "rcu"
    "strings"
)

var grid = [][]int {
    { 8,  2, 22, 97, 38, 15,  0, 40,  0, 75,  4,  5,  7, 78, 52, 12, 50, 77, 91,  8},
    {49, 49, 99, 40, 17, 81, 18, 57, 60, 87, 17, 40, 98, 43, 69, 48,  4, 56, 62,  0},
    {81, 49, 31, 73, 55, 79, 14, 29, 93, 71, 40, 67, 53, 88, 30,  3, 49, 13, 36, 65},
    {52, 70, 95, 23,  4, 60, 11, 42, 69, 24, 68, 56,  1, 32, 56, 71, 37,  2, 36, 91},
    {22, 31, 16, 71, 51, 67, 63, 89, 41, 92, 36, 54, 22, 40, 40, 28, 66, 33, 13, 80},
    {24, 47, 32, 60, 99,  3, 45,  2, 44, 75, 33, 53, 78, 36, 84, 20, 35, 17, 12, 50},
    {32, 98, 81, 28, 64, 23, 67, 10, 26, 38, 40, 67, 59, 54, 70, 66, 18, 38, 64, 70},
    {67, 26, 20, 68,  2, 62, 12, 20, 95, 63, 94, 39, 63,  8, 40, 91, 66, 49, 94, 21},
    {24, 55, 58,  5, 66, 73, 99, 26, 97, 17, 78, 78, 96, 83, 14, 88, 34, 89, 63, 72},
    {21, 36, 23,  9, 75,  0, 76, 44, 20, 45, 35, 14,  0, 61, 33, 97, 34, 31, 33, 95},
    {78, 17, 53, 28, 22, 75, 31, 67, 15, 94,  3, 80,  4, 62, 16, 14,  9, 53, 56, 92},
    {16, 39,  5, 42, 96, 35, 31, 47, 55, 58, 88, 24,  0, 17, 54, 24, 36, 29, 85, 57},
    {86, 56,  0, 48, 35, 71, 89,  7,  5, 44, 44, 37, 44, 60, 21, 58, 51, 54, 17, 58},
    {19, 80, 81, 68,  5, 94, 47, 69, 28, 73, 92, 13, 86, 52, 17, 77,  4, 89, 55, 40},
    { 4, 52,  8, 83, 97, 35, 99, 16,  7, 97, 57, 32, 16, 26, 26, 79, 33, 27, 98, 66},
    {88, 36, 68, 87, 57, 62, 20, 72,  3, 46, 33, 67, 46, 55, 12, 32, 63, 93, 53, 69},
    { 4, 42, 16, 73, 38, 25, 39, 11, 24, 94, 72, 18,  8, 46, 29, 32, 40, 62, 76, 36},
    {20, 69, 36, 41, 72, 30, 23, 88, 34, 62, 99, 69, 82, 67, 59, 85, 74,  4, 36, 16},
    {20, 73, 35, 29, 78, 31, 90,  1, 74, 31, 49, 71, 48, 86, 81, 16, 23, 57,  5, 54},
    { 1, 70, 54, 71, 83, 51, 54, 69, 16, 92, 33, 48, 61, 43, 52,  1, 89, 19, 67, 48},
}

func main() {
    maxProd, maxR1, maxR2, maxC1, maxC2 := 0, 0, 0, 0, 0
    var maxNums [4]int
    h, w := len(grid), len(grid[0])

    // right
    for r := 0; r < h; r++ {
        for c := 0; c < w-4; c++ {
            prod := 1
            for i := c; i < c+4; i++ {
                prod *= grid[r][i]
            }
            if prod > maxProd {
                maxProd = prod
                for n := 0; n < 4; n++ {
                    maxNums[n] = grid[r][c+n]
                }
                maxR1, maxR2 = r, r
                maxC1, maxC2 = c, c+3
            }
        }
    }

    // down
    for c := 0; c < w; c++ {
        for r := 0; r < h-4; r++ {
            prod := 1
            for i := r; i < r+4; i++ {
                prod *= grid[i][c]
            }
            if prod > maxProd {
                maxProd = prod
                for n := 0; n < 4; n++ {
                    maxNums[n] = grid[r+n][c]
                }
                maxR1, maxR2 = r, r+3
                maxC1, maxC2 = c, c
            }
        }
    }

    fmt.Println("The greatest product of four adjacent numbers in the same direction (down or right) in the grid is:")
    var maxNumStrs [4]string
    for i := 0; i < 4; i++ {
        maxNumStrs[i] = fmt.Sprintf("%d", maxNums[i])
    }
    fmt.Printf("  %s = %s\n", strings.Join(maxNumStrs[:], " x "), rcu.Commatize(maxProd))
    fmt.Print("  at indices (one based): ")
    for r := maxR1; r <= maxR2; r++ {
        for c := maxC1; c <= maxC2; c++ {
            fmt.Printf("(%d, %d) ", r+1, c+1)
        }
    }
    fmt.Println()
}

Output:

The greatest product of four adjacent numbers in the same direction (down or right) in the grid is:
  66 x 91 x 88 x 97 = 51,267,216
  at indices (one based): (7, 16) (8, 16) (9, 16) (10, 16) 

Haskell

import Data.List.Split ( divvy )
import Data.List ( transpose )   

grid :: [String]
grid =["08 02 22 97 38 15 00 40 00 75 04 05 07 78 52 12 50 77 91 08" ,
 "49 49 99 40 17 81 18 57 60 87 17 40 98 43 69 48 04 56 62 00",
 "81 49 31 73 55 79 14 29 93 71 40 67 53 88 30 03 49 13 36 65",
 "52 70 95 23 04 60 11 42 69 24 68 56 01 32 56 71 37 02 36 9",
 "22 31 16 71 51 67 63 89 41 92 36 54 22 40 40 28 66 33 13 80",
 "24 47 32 60 99 03 45 02 44 75 33 53 78 36 84 20 35 17 12 50",
 "32 98 81 28 64 23 67 10 26 38 40 67 59 54 70 66 18 38 64 70",
 "67 26 20 68 02 62 12 20 95 63 94 39 63 08 40 91 66 49 94 21",
 "24 55 58 05 66 73 99 26 97 17 78 78 96 83 14 88 34 89 63 72",
 "21 36 23 09 75 00 76 44 20 45 35 14 00 61 33 97 34 31 33 95",
 "78 17 53 28 22 75 31 67 15 94 03 80 04 62 16 14 09 53 56 92",
 "16 39 05 42 96 35 31 47 55 58 88 24 00 17 54 24 36 29 85 57",
 "86 56 00 48 35 71 89 07 05 44 44 37 44 60 21 58 51 54 17 58",
 "19 80 81 68 05 94 47 69 28 73 92 13 86 52 17 77 04 89 55 40",
 "04 52 08 83 97 35 99 16 07 97 57 32 16 26 26 79 33 27 98 66",
 "88 36 68 87 57 62 20 72 03 46 33 67 46 55 12 32 63 93 53 69",
 "04 42 16 73 38 25 39 11 24 94 72 18 08 46 29 32 40 62 76 36",
 "20 69 36 41 72 30 23 88 34 62 99 69 82 67 59 85 74 04 36 16",
 "20 73 35 29 78 31 90 01 74 31 49 71 48 86 81 16 23 57 05 54",
 "01 70 54 71 83 51 54 69 16 92 33 48 61 43 52 01 89 19 67 48"]

toMatrix :: [String] -> [[Int]]
toMatrix = map ( map read . words )

maxHorizontal :: [[Int]] -> Int
maxHorizontal = maximum . map product . divvy 4 1  . concat

maxTotal :: [[Int]] -> Int
maxTotal matrix = max ( maxHorizontal matrix ) ( maxHorizontal $ transpose
 matrix )

main :: IO ( ) 
main = do
   print $ maxTotal $ toMatrix grid

Output:

51267216

J

First, the "hard part" -- represent the grid itself:

grid=: ".>cutLF{{)n
08 02 22 97 38 15 00 40 00 75 04 05 07 78 52 12 50 77 91 08
49 49 99 40 17 81 18 57 60 87 17 40 98 43 69 48 04 56 62 00
81 49 31 73 55 79 14 29 93 71 40 67 53 88 30 03 49 13 36 65
52 70 95 23 04 60 11 42 69 24 68 56 01 32 56 71 37 02 36 91
22 31 16 71 51 67 63 89 41 92 36 54 22 40 40 28 66 33 13 80
24 47 32 60 99 03 45 02 44 75 33 53 78 36 84 20 35 17 12 50
32 98 81 28 64 23 67 10 26 38 40 67 59 54 70 66 18 38 64 70
67 26 20 68 02 62 12 20 95 63 94 39 63 08 40 91 66 49 94 21
24 55 58 05 66 73 99 26 97 17 78 78 96 83 14 88 34 89 63 72
21 36 23 09 75 00 76 44 20 45 35 14 00 61 33 97 34 31 33 95
78 17 53 28 22 75 31 67 15 94 03 80 04 62 16 14 09 53 56 92
16 39 05 42 96 35 31 47 55 58 88 24 00 17 54 24 36 29 85 57
86 56 00 48 35 71 89 07 05 44 44 37 44 60 21 58 51 54 17 58
19 80 81 68 05 94 47 69 28 73 92 13 86 52 17 77 04 89 55 40
04 52 08 83 97 35 99 16 07 97 57 32 16 26 26 79 33 27 98 66
88 36 68 87 57 62 20 72 03 46 33 67 46 55 12 32 63 93 53 69
04 42 16 73 38 25 39 11 24 94 72 18 08 46 29 32 40 62 76 36
20 69 36 41 72 30 23 88 34 62 99 69 82 67 59 85 74 04 36 16
20 73 35 29 78 31 90 01 74 31 49 71 48 86 81 16 23 57 05 54
01 70 54 71 83 51 54 69 16 92 33 48 61 43 52 01 89 19 67 48
}}

With that out of the way, we find all products of four numbers and then find the largest of those:

   >./,4 */\ (,.|:)grid
51267216

If we wanted to find which four numbers formed this product, we could do a little more work:

   ($ #: I.@,) (= >./@,)4 */\ (,.|:)grid
6 15

This tells us that the four number sequence started at row 6 (row 0 is the first row) and column 15. This also means that the numbers extend downwards from there. (If the column index had been 20 or higher, the number sequence would have come from the transposed copy of the array, so they would have been arranged left to right in the original 'grid'.)

In other words:

   (6 7 8 9 ,&.> 15) { grid
66 91 88 97
   */66 91 88 97
51267216

Java

import java.util.ArrayList;
import java.util.List;
import java.util.stream.LongStream;

public final class LargestProductInAGrid {

	public static void main(String[] args) {
		final long[][] grid = new long[][] {
            {  8,  2, 22, 97, 38, 15,  0, 40,  0, 75,  4,  5,  7, 78, 52, 12, 50, 77, 91,  8 },
            { 49, 49, 99, 40, 17, 81, 18, 57, 60, 87, 17, 40, 98, 43, 69, 48,  4, 56, 62,  0 },
            { 81, 49, 31, 73, 55, 79, 14, 29, 93, 71, 40, 67, 53, 88, 30,  3, 49, 13, 36, 65 },
            { 52, 70, 95, 23,  4, 60, 11, 42, 69, 24, 68, 56,  1, 32, 56, 71, 37,  2, 36, 91 },
            { 22, 31, 16, 71, 51, 67, 63, 89, 41, 92, 36, 54, 22, 40, 40, 28, 66, 33, 13, 80 },
            { 24, 47, 32, 60, 99,  3, 45,  2, 44, 75, 33, 53, 78, 36, 84, 20, 35, 17, 12, 50 },
            { 32, 98, 81, 28, 64, 23, 67, 10, 26, 38, 40, 67, 59, 54, 70, 66, 18, 38, 64, 70 },
            { 67, 26, 20, 68,  2, 62, 12, 20, 95, 63, 94, 39, 63,  8, 40, 91, 66, 49, 94, 21 },
            { 24, 55, 58,  5, 66, 73, 99, 26, 97, 17, 78, 78, 96, 83, 14, 88, 34, 89, 63, 72 },
            { 21, 36, 23,  9, 75,  0, 76, 44, 20, 45, 35, 14,  0, 61, 33, 97, 34, 31, 33, 95 },
            { 78, 17, 53, 28, 22, 75, 31, 67, 15, 94,  3, 80,  4, 62, 16, 14,  9, 53, 56, 92 },
            { 16, 39,  5, 42, 96, 35, 31, 47, 55, 58, 88, 24,  0, 17, 54, 24, 36, 29, 85, 57 },
            { 86, 56,  0, 48, 35, 71, 89,  7,  5, 44, 44, 37, 44, 60, 21, 58, 51, 54, 17, 58 },
            { 19, 80, 81, 68,  5, 94, 47, 69, 28, 73, 92, 13, 86, 52, 17, 77,  4, 89, 55, 40 },
            {  4, 52,  8, 83, 97, 35, 99, 16,  7, 97, 57, 32, 16, 26, 26, 79, 33, 27, 98, 66 },
            { 88, 36, 68, 87, 57, 62, 20, 72,  3, 46, 33, 67, 46, 55, 12, 32, 63, 93, 53, 69 },
            {  4, 42, 16, 73, 38, 25, 39, 11, 24, 94, 72, 18,  8, 46, 29, 32, 40, 62, 76, 36 },
            { 20, 69, 36, 41, 72, 30, 23, 88, 34, 62, 99, 69, 82, 67, 59, 85, 74,  4, 36, 16 },
            { 20, 73, 35, 29, 78, 31, 90,  1, 74, 31, 49, 71, 48, 86, 81, 16, 23, 57,  5, 54 },
            {  1, 70, 54, 71, 83, 51, 54, 69, 16, 92, 33, 48, 61, 43, 52,  1, 89, 19, 67, 48 }
        };
        
        for ( int n = 2; n <= 5; n++ ) {
            maxProduct(grid, n);
        }
    }
	
	private static void maxProduct(long[][] grid, int productLength) {
		final int rowCount = grid.length;
		final int colCount = grid[0].length;
		
		long maxProduct = 0;
		Coordinate maxRow = new Coordinate(0, 0);
		Coordinate maxCol = new Coordinate(0, 0);
		List<Long> numbers = new ArrayList<Long>();
	    
		for ( int row = 0; row < rowCount; row++ ) {
			for ( int col = 0; col < colCount; col++ ) {		
	            final int row2 = row + productLength;
	            final int col2 = col + productLength;

	            if  ( row < rowCount - productLength ) {
	            	final int colFixed = col;   
	            	final long product = LongStream.range(row, row2).map( r -> grid[(int) r][colFixed] )
	            			                       .reduce(1, Math::multiplyExact);   
	                if ( product > maxProduct ) {
	                	maxProduct = product;
	                	maxRow = new Coordinate(row, row2);
	                	maxCol = new Coordinate(col, -1);
	                	numbers = LongStream.range(row, row2).map( r -> grid[(int) r][colFixed] ).boxed().toList();
	                }
	            }

	            if ( col < colCount - productLength ) {
	            	final int rowFixed = row;
	                final long product = LongStream.range(col, col2).map( c -> grid[rowFixed][(int) c] )
	                		                       .reduce(1, Math::multiplyExact);
	                if ( product > maxProduct ) {
	                	maxProduct = product;
	                	maxRow = new Coordinate(row, -1);
	                	maxCol = new Coordinate(col, col2);
	                	numbers = LongStream.range(col, col2).map( c -> grid[rowFixed][(int) c] ).boxed().toList();
	                }
	            }
	        }
		}

	    System.out.println("The maximum " + productLength + "-product is " + maxProduct
	    	+ ", product of " + numbers + " at row " + maxRow + ", col " + maxCol);
	}
	
	private static record Coordinate(int x, int y) {
		
		public String toString() {
			if ( y == -1 ) {
				return String.valueOf(x);
			}
			return "(" + x + ", " + y + ")";
		}
		
	}

}

Output:

The maximum 2-product is 9215, product of [95, 97] at row (7, 9), col 8
The maximum 3-product is 776776, product of [91, 88, 97] at row (7, 10), col 15
The maximum 4-product is 51267216, product of [66, 91, 88, 97] at row (6, 10), col 15
The maximum 5-product is 2326829868, product of [62, 99, 69, 82, 67] at row 17, col (9, 14)

JavaScript

ES5

Works with: Node.js

Translation of: C

// Largest product in a grid
const prodLen = 4;
const gridSize = 20;
const jMax = gridSize - prodLen;

const grid =
  [ [ 8,  2, 22, 97, 38, 15,  0, 40,  0, 75,  4,  5,  7, 78, 52, 12, 50, 77, 91,  8], 
    [49, 49, 99, 40, 17, 81, 18, 57, 60, 87, 17, 40, 98, 43, 69, 48,  4, 56, 62,  0], 
    [81, 49, 31, 73, 55, 79, 14, 29, 93, 71, 40, 67, 53, 88, 30,  3, 49, 13, 36, 65], 
    [52, 70, 95, 23,  4, 60, 11, 42, 69, 24, 68, 56,  1, 32, 56, 71, 37,  2, 36, 91], 
    [22, 31, 16, 71, 51, 67, 63, 89, 41, 92, 36, 54, 22, 40, 40, 28, 66, 33, 13, 80], 
    [24, 47, 32, 60, 99,  3, 45,  2, 44, 75, 33, 53, 78, 36, 84, 20, 35, 17, 12, 50], 
    [32, 98, 81, 28, 64, 23, 67, 10, 26, 38, 40, 67, 59, 54, 70, 66, 18, 38, 64, 70], 
    [67, 26, 20, 68,  2, 62, 12, 20, 95, 63, 94, 39, 63,  8, 40, 91, 66, 49, 94, 21], 
    [24, 55, 58,  5, 66, 73, 99, 26, 97, 17, 78, 78, 96, 83, 14, 88, 34, 89, 63, 72], 
    [21, 36, 23,  9, 75,  0, 76, 44, 20, 45, 35, 14,  0, 61, 33, 97, 34, 31, 33, 95], 
    [78, 17, 53, 28, 22, 75, 31, 67, 15, 94,  3, 80,  4, 62, 16, 14,  9, 53, 56, 92], 
    [16, 39,  5, 42, 96, 35, 31, 47, 55, 58, 88, 24,  0, 17, 54, 24, 36, 29, 85, 57], 
    [86, 56,  0, 48, 35, 71, 89,  7,  5, 44, 44, 37, 44, 60, 21, 58, 51, 54, 17, 58], 
    [19, 80, 81, 68,  5, 94, 47, 69, 28, 73, 92, 13, 86, 52, 17, 77,  4, 89, 55, 40], 
    [ 4, 52,  8, 83, 97, 35, 99, 16,  7, 97, 57, 32, 16, 26, 26, 79, 33, 27, 98, 66], 
    [88, 36, 68, 87, 57, 62, 20, 72,  3, 46, 33, 67, 46, 55, 12, 32, 63, 93, 53, 69], 
    [ 4, 42, 16, 73, 38, 25, 39, 11, 24, 94, 72, 18,  8, 46, 29, 32, 40, 62, 76, 36], 
    [20, 69, 36, 41, 72, 30, 23, 88, 34, 62, 99, 69, 82, 67, 59, 85, 74,  4, 36, 16], 
    [20, 73, 35, 29, 78, 31, 90,  1, 74, 31, 49, 71, 48, 86, 81, 16, 23, 57,  5, 54], 
    [ 1, 70, 54, 71, 83, 51, 54, 69, 16, 92, 33, 48, 61, 43, 52,  1, 89, 19, 67, 48] ];
  
let max = 0;
for (let j = 0; j < gridSize; j++)
  for (let i = 0; i <= jMax; i++)
    for (let k = i, prod = 1, kMax = prodLen + i - 1; k <= kMax; k++) { 
      prod *= grid[j][k];
      if (prod > max) 
        max = prod;
    }
for (let j = 0; j <= jMax; j++)
  for (let i = 0; i < gridSize; i++)
    for (let k = j, prod = 1, kMax = prodLen + j - 1; k <= kMax; k++) { 
      prod *= grid[k][i];
      if (prod > max) 
        max = prod;
    }
console.log(max);

Output:

51267216

jq

Works with both jq and gojq, the C and Go implementations of jq

In Part 1 below, a simple solution to the basic problem, namely finding the maximum value, is presented.

In Part 2, the focus shifts to reporting the location and direction of the elements with the maximal product. Arrays are indexed from 0.

In both cases, it is assumed that `grid` has been defined as a function returning the grid as an array of arrays as presented, for example, in the Wren entry.

Generic Utilities

def prod(s): reduce s as $x (1; . * $x);
def prod: prod(.[]);

# Input: an array
# Output: a stream of arrays
def windows($size): range(0; 1+length-$size) as $i | .[$i:$i+$size];

Part 1

# Input: a matrix
def largest_product($size):
   ([.[] |  (windows($size) | prod)] | max) as $rowmax
   |  ([transpose[] | (windows($size) | prod)] | max) as $colmax
   | [$rowmax, $colmax]|max,
     if ($rowmax > $colmax) then "The rows have it." else "The columns
   have it." end ;

grid | largest_product(4)

Output:

51267216
The columns have it.

Part 2

# Input: a row
# Output: [$i, $maxproduct]
def largest_product_of_row($size):
   [range(0; 1 + length - $size) as $i
    | [$i, (.[$i:$i+$size] | prod)] ] | max_by(.[1]);

# Input: a matrix
def largest_product_of_rows($size):
  [range(0; length) as $row
   | [$row, (.[$row] | largest_product_of_row($size)) ]] | max_by(.[1][1])
   | [ .[0], .[1][]] ;

# Input: a matrix
def largest_product_with_details($size):
  largest_product_of_rows($size) as [$row, $rowcol, $rmax]
  | (transpose | largest_product_of_rows($size)) as [$col, $colrow, $cmax]
  | if $rmax == $cmax
    then "row-wise at \([$row, $rowcol]) equals col-wise at \([$col, $colrow]): \($cmax)"
    elif $rmax > $cmax then "The rows have it at \([$row, $rowcol]): \($rmax)"
    else                 "The columns have it at \([$colrow, $col]): \($cmax)"
    end ;    

grid | largest_product_with_details(4)

Output:

The columns have it at [6,15]: 51267216

Julia

First, a quick method, which does not reveal the product locations:

mat = [
    08 02 22 97 38 15 00 40 00 75 04 05 07 78 52 12 50 77 91 08
    49 49 99 40 17 81 18 57 60 87 17 40 98 43 69 48 04 56 62 00
    81 49 31 73 55 79 14 29 93 71 40 67 53 88 30 03 49 13 36 65
    52 70 95 23 04 60 11 42 69 24 68 56 01 32 56 71 37 02 36 91
    22 31 16 71 51 67 63 89 41 92 36 54 22 40 40 28 66 33 13 80
    24 47 32 60 99 03 45 02 44 75 33 53 78 36 84 20 35 17 12 50
    32 98 81 28 64 23 67 10 26 38 40 67 59 54 70 66 18 38 64 70
    67 26 20 68 02 62 12 20 95 63 94 39 63 08 40 91 66 49 94 21
    24 55 58 05 66 73 99 26 97 17 78 78 96 83 14 88 34 89 63 72
    21 36 23 09 75 00 76 44 20 45 35 14 00 61 33 97 34 31 33 95
    78 17 53 28 22 75 31 67 15 94 03 80 04 62 16 14 09 53 56 92
    16 39 05 42 96 35 31 47 55 58 88 24 00 17 54 24 36 29 85 57
    86 56 00 48 35 71 89 07 05 44 44 37 44 60 21 58 51 54 17 58
    19 80 81 68 05 94 47 69 28 73 92 13 86 52 17 77 04 89 55 40
    04 52 08 83 97 35 99 16 07 97 57 32 16 26 26 79 33 27 98 66
    88 36 68 87 57 62 20 72 03 46 33 67 46 55 12 32 63 93 53 69
    04 42 16 73 38 25 39 11 24 94 72 18 08 46 29 32 40 62 76 36
    20 69 36 41 72 30 23 88 34 62 99 69 82 67 59 85 74 04 36 16
    20 73 35 29 78 31 90 01 74 31 49 71 48 86 81 16 23 57 05 54
    01 70 54 71 83 51 54 69 16 92 33 48 61 43 52 01 89 19 67 48
]

x = max(maximum([prod(mat[j, i:i+3]) for i in 1:17, j in 1:20]),
    maximum([prod(mat[i:i+3, j]) for i in 1:17, j in 1:20]))
println("The maximum product of 4 adjacent horizontal or vertical in the matrix is: $x")

Output:

The maximum product of 4 adjacent horizontal or vertical in the matrix is: 51267216

Alternatively, to get the position of the maximum product:

function maxprod(mat, len)
    nrow, ncol = size(mat)
    maxprod, maxrow, maxcol, arr = 0, 0:0, 0:0, [0]
    for row in 1:nrow, col in 1:ncol
        if row < nrow - len + 2
            pro = prod(mat[row:row+len-1, col])
            if pro > maxprod
                maxprod, maxrow, maxcol, arr = pro, row:row+len-1, col:col, mat[row:row+len-1, col]
            end
        end
        if col < ncol - len + 2
            pro = prod(mat[row, col:col+len-1])
            if pro > maxprod
                maxprod, maxrow, maxcol, arr = pro, row:row, col:col+len-1, mat[row, col:col+len-1]
            end
        end
    end
    println("The maximum product is $maxprod, product of $arr at row $maxrow, col $maxcol")
end

maxprod(mat, 4)

Output:

The maximum product is 51267216, product of [66, 91, 88, 97] at row 7:10, col 16:16

Mathematica / Wolfram Language

array = {
   {08, 02, 22, 97, 38, 15, 00, 40, 00, 75, 04, 05, 07, 78, 52, 12, 
    50, 77, 91, 08},
   {49, 49, 99, 40, 17, 81, 18, 57, 60, 87, 17, 40, 98, 43, 69, 48, 
    04, 56, 62, 00},
   {81, 49, 31, 73, 55, 79, 14, 29, 93, 71, 40, 67, 53, 88, 30, 03, 
    49, 13, 36, 65},
   {52, 70, 95, 23, 04, 60, 11, 42, 69, 24, 68, 56, 01, 32, 56, 71, 
    37, 02, 36, 91},
   {22, 31, 16, 71, 51, 67, 63, 89, 41, 92, 36, 54, 22, 40, 40, 28, 
    66, 33, 13, 80},
   {24, 47, 32, 60, 99, 03, 45, 02, 44, 75, 33, 53, 78, 36, 84, 20, 
    35, 17, 12, 50},
   {32, 98, 81, 28, 64, 23, 67, 10, 26, 38, 40, 67, 59, 54, 70, 66, 
    18, 38, 64, 70},
   {67, 26, 20, 68, 02, 62, 12, 20, 95, 63, 94, 39, 63, 08, 40, 91, 
    66, 49, 94, 21},
   {24, 55, 58, 05, 66, 73, 99, 26, 97, 17, 78, 78, 96, 83, 14, 88, 
    34, 89, 63, 72},
   {21, 36, 23, 09, 75, 00, 76, 44, 20, 45, 35, 14, 00, 61, 33, 97, 
    34, 31, 33, 95},
   {78, 17, 53, 28, 22, 75, 31, 67, 15, 94, 03, 80, 04, 62, 16, 14, 
    09, 53, 56, 92},
   {16, 39, 05, 42, 96, 35, 31, 47, 55, 58, 88, 24, 00, 17, 54, 24, 
    36, 29, 85, 57},
   {86, 56, 00, 48, 35, 71, 89, 07, 05, 44, 44, 37, 44, 60, 21, 58, 
    51, 54, 17, 58},
   {19, 80, 81, 68, 05, 94, 47, 69, 28, 73, 92, 13, 86, 52, 17, 77, 
    04, 89, 55, 40},
   {04, 52, 08, 83, 97, 35, 99, 16, 07, 97, 57, 32, 16, 26, 26, 79, 
    33, 27, 98, 66},
   {88, 36, 68, 87, 57, 62, 20, 72, 03, 46, 33, 67, 46, 55, 12, 32, 
    63, 93, 53, 69},
   {04, 42, 16, 73, 38, 25, 39, 11, 24, 94, 72, 18, 08, 46, 29, 32, 
    40, 62, 76, 36},
   {20, 69, 36, 41, 72, 30, 23, 88, 34, 62, 99, 69, 82, 67, 59, 85, 
    74, 04, 36, 16},
   {20, 73, 35, 29, 78, 31, 90, 01, 74, 31, 49, 71, 48, 86, 81, 16, 
    23, 57, 05, 54},
   {01, 70, 54, 71, 83, 51, 54, 69, 16, 92, 33, 48, 61, 43, 52, 01, 
    89, 19, 67, 48}
   };
   maxProduct[x_List, n_] := Max[Times @@@ Partition[x, n, 1]]
Max@Join[maxProduct[#, 4] & /@ array, 
  maxProduct[#, 4] & /@ Transpose[array]]

Output:

51267216

Modula-2

Translation of: C

Works with: ADW Modula-2 version any (Compile with the linker option Console Application).

MODULE LargProdGrid;
(* Largest product in a grid *)
FROM SWholeIO IMPORT
  WriteInt;
FROM STextIO IMPORT
  WriteLn;

CONST
  ProdLen = 4;
  GridSize = 20;
  JMax = GridSize - ProdLen;

TYPE
  TGrid = ARRAY [0 .. GridSize - 1], [0 .. GridSize - 1] OF INTEGER;

VAR
  Grid: TGrid;
  I, J, K, KMax: CARDINAL;
  Max, Prod: INTEGER;
BEGIN
  Grid := TGrid{
      { 8,  2, 22, 97, 38, 15,  0, 40,  0, 75,  4,  5,  7, 78, 52, 12, 50, 77, 91,  8},
      {49, 49, 99, 40, 17, 81, 18, 57, 60, 87, 17, 40, 98, 43, 69, 48,  4, 56, 62,  0},
      {81, 49, 31, 73, 55, 79, 14, 29, 93, 71, 40, 67, 53, 88, 30,  3, 49, 13, 36, 65},
      {52, 70, 95, 23,  4, 60, 11, 42, 69, 24, 68, 56,  1, 32, 56, 71, 37,  2, 36, 91},
      {22, 31, 16, 71, 51, 67, 63, 89, 41, 92, 36, 54, 22, 40, 40, 28, 66, 33, 13, 80},
      {24, 47, 32, 60, 99,  3, 45,  2, 44, 75, 33, 53, 78, 36, 84, 20, 35, 17, 12, 50},
      {32, 98, 81, 28, 64, 23, 67, 10, 26, 38, 40, 67, 59, 54, 70, 66, 18, 38, 64, 70},
      {67, 26, 20, 68,  2, 62, 12, 20, 95, 63, 94, 39, 63,  8, 40, 91, 66, 49, 94, 21},
      {24, 55, 58,  5, 66, 73, 99, 26, 97, 17, 78, 78, 96, 83, 14, 88, 34, 89, 63, 72},
      {21, 36, 23,  9, 75,  0, 76, 44, 20, 45, 35, 14,  0, 61, 33, 97, 34, 31, 33, 95},
      {78, 17, 53, 28, 22, 75, 31, 67, 15, 94,  3, 80,  4, 62, 16, 14,  9, 53, 56, 92},
      {16, 39,  5, 42, 96, 35, 31, 47, 55, 58, 88, 24,  0, 17, 54, 24, 36, 29, 85, 57},
      {86, 56,  0, 48, 35, 71, 89,  7,  5, 44, 44, 37, 44, 60, 21, 58, 51, 54, 17, 58},
      {19, 80, 81, 68,  5, 94, 47, 69, 28, 73, 92, 13, 86, 52, 17, 77,  4, 89, 55, 40},
      { 4, 52,  8, 83, 97, 35, 99, 16,  7, 97, 57, 32, 16, 26, 26, 79, 33, 27, 98, 66},
      {88, 36, 68, 87, 57, 62, 20, 72,  3, 46, 33, 67, 46, 55, 12, 32, 63, 93, 53, 69},
      { 4, 42, 16, 73, 38, 25, 39, 11, 24, 94, 72, 18,  8, 46, 29, 32, 40, 62, 76, 36},
      {20, 69, 36, 41, 72, 30, 23, 88, 34, 62, 99, 69, 82, 67, 59, 85, 74,  4, 36, 16},
      {20, 73, 35, 29, 78, 31, 90,  1, 74, 31, 49, 71, 48, 86, 81, 16, 23, 57,  5, 54},
      { 1, 70, 54, 71, 83, 51, 54, 69, 16, 92, 33, 48, 61, 43, 52,  1, 89, 19, 67, 48} };

  Max := 0;
  FOR J := 0 TO GridSize - 1 DO
    FOR I := 0 TO JMax DO
      Prod := 1;
      KMax := ProdLen + I - 1;
      FOR K := I TO KMax DO
        Prod := Prod * Grid[J, K];
        IF Prod > Max THEN
          Max := Prod
        END
      END
    END
  END;
  FOR J := 0 TO JMax DO
    FOR I := 0 TO GridSize - 1 DO
      Prod := 1;
      KMax := ProdLen + J - 1;
      FOR K := J TO KMax DO
        Prod := Prod * Grid[K, I];
        IF Prod > Max THEN
          Max := Prod
        END
      END;
    END;
  END;
  WriteInt(Max, 1);
  WriteLn
END LargProdGrid.

Output:

51267216

ooRexx

/* REXX */
a.1=.array~of(08,02,22,97,38,15,00,40,00,75,04,05,07,78,52,12,50,77,91,08)
a.2=.array~of(49,49,99,40,17,81,18,57,60,87,17,40,98,43,69,48,04,56,62,00)
a.3=.array~of(81,49,31,73,55,79,14,29,93,71,40,67,53,88,30,03,49,13,36,65)
a.4=.array~of(52,70,95,23,04,60,11,42,69,24,68,56,01,32,56,71,37,02,36,91)
a.5=.array~of(22,31,16,71,51,67,63,89,41,92,36,54,22,40,40,28,66,33,13,80)
a.6=.array~of(24,47,32,60,99,03,45,02,44,75,33,53,78,36,84,20,35,17,12,50)
a.7=.array~of(32,98,81,28,64,23,67,10,26,38,40,67,59,54,70,66,18,38,64,70)
a.8=.array~of(67,26,20,68,02,62,12,20,95,63,94,39,63,08,40,91,66,49,94,21)
a.9=.array~of(24,55,58,05,66,73,99,26,97,17,78,78,96,83,14,88,34,89,63,72)
a.10=.array~of(21,36,23,09,75,00,76,44,20,45,35,14,00,61,33,97,34,31,33,95)
a.11=.array~of(78,17,53,28,22,75,31,67,15,94,03,80,04,62,16,14,09,53,56,92)
a.12=.array~of(16,39,05,42,96,35,31,47,55,58,88,24,00,17,54,24,36,29,85,57)
a.13=.array~of(86,56,00,48,35,71,89,07,05,44,44,37,44,60,21,58,51,54,17,58)
a.14=.array~of(19,80,81,68,05,94,47,69,28,73,92,13,86,52,17,77,04,89,55,40)
a.15=.array~of(04,52,08,83,97,35,99,16,07,97,57,32,16,26,26,79,33,27,98,66)
a.16=.array~of(88,36,68,87,57,62,20,72,03,46,33,67,46,55,12,32,63,93,53,69)
a.17=.array~of(04,42,16,73,38,25,39,11,24,94,72,18,08,46,29,32,40,62,76,36)
a.18=.array~of(20,69,36,41,72,30,23,88,34,62,99,69,82,67,59,85,74,04,36,16)
a.19=.array~of(20,73,35,29,78,31,90,01,74,31,49,71,48,86,81,16,23,57,05,54)
a.20=.array~of(01,70,54,71,83,51,54,69,16,92,33,48,61,43,52,01,89,19,67,48)
max=0
Do row=1 To 20
  Do col=1 To 17
    ar=a.row
    prod=ar[col]*ar[col+1]*ar[col+2]*ar[col+3]
    If prod>max Then Do
      max=prod
      rc=row col
      l=ar[col]'*'ar[col+1]'*'ar[col+2]'*'ar[col+3]'='prod
      End
    End
  End
Parse Var rc row col
Say 'Maximum in row' row 'columns' col '...' (col+3) ':' l
Do i=1 To 20
  b.i=.array~of(a.1[i],a.2[i],a.3[i],a.4[i],a.5[i],a.6[i],a.7[i],a.8[i],a.9[i],a.10[i],,
      a.11[i],a.12[i],a.13[i],a.14[i],a.15[i],a.16[i],a.17[i],a.18[i],a.19[i],a.20[i])
  End
Do col=1 to 20
  Do row=1 To 17
    bc=b.col
    prod=bc[row]*bc[row+1]*bc[row+2]*bc[row+3]
    If prod>max Then Do
      max=prod
      rc=row col
      l=bc[row]'*'bc[row+1]'*'bc[row+2]'*'bc[row+3]'='prod
      End
    End
  End
Parse Var rc row col
Say 'Maximum in column' col 'rows' row '...' (row+3)
Say l

Output:

Maximum in row 9 columns 11 ... 14 : 78*78*96*83=48477312
Maximum in column 16 rows 7 ... 10 : 66*91*88*97=51267216

Perl

#!/usr/bin/perl

use strict; # https://rosettacode.org/wiki/Largest_product_in_a_grid
use warnings;
use List::Util qw( max );

$_ = <<END;
08 02 22 97 38 15 00 40 00 75 04 05 07 78 52 12 50 77 91 08
49 49 99 40 17 81 18 57 60 87 17 40 98 43 69 48 04 56 62 00
81 49 31 73 55 79 14 29 93 71 40 67 53 88 30 03 49 13 36 65
52 70 95 23 04 60 11 42 69 24 68 56 01 32 56 71 37 02 36 91
22 31 16 71 51 67 63 89 41 92 36 54 22 40 40 28 66 33 13 80
24 47 32 60 99 03 45 02 44 75 33 53 78 36 84 20 35 17 12 50
32 98 81 28 64 23 67 10 26 38 40 67 59 54 70 66 18 38 64 70
67 26 20 68 02 62 12 20 95 63 94 39 63 08 40 91 66 49 94 21
24 55 58 05 66 73 99 26 97 17 78 78 96 83 14 88 34 89 63 72
21 36 23 09 75 00 76 44 20 45 35 14 00 61 33 97 34 31 33 95
78 17 53 28 22 75 31 67 15 94 03 80 04 62 16 14 09 53 56 92
16 39 05 42 96 35 31 47 55 58 88 24 00 17 54 24 36 29 85 57
86 56 00 48 35 71 89 07 05 44 44 37 44 60 21 58 51 54 17 58
19 80 81 68 05 94 47 69 28 73 92 13 86 52 17 77 04 89 55 40
04 52 08 83 97 35 99 16 07 97 57 32 16 26 26 79 33 27 98 66
88 36 68 87 57 62 20 72 03 46 33 67 46 55 12 32 63 93 53 69
04 42 16 73 38 25 39 11 24 94 72 18 08 46 29 32 40 62 76 36
20 69 36 41 72 30 23 88 34 62 99 69 82 67 59 85 74 04 36 16
20 73 35 29 78 31 90 01 74 31 49 71 48 86 81 16 23 57 05 54
01 70 54 71 83 51 54 69 16 92 33 48 61 43 52 01 89 19 67 48
END

my $score = 0;
for my $gap ( qr/ /, qr/.{58}/s )
  {
  $score = max $score, $1 * $2 * $3 * $4
    while /(?=(\d\d)$gap(\d\d)$gap(\d\d)$gap(\d\d))/g;
  }
print "max is $score\n";

Output:

max is 51267216

Generalized

Handles non-square input (both narrow and wide).

use strict;
use warnings;
use feature 'say';
use List::AllUtils <max reduce>;

my $input = <<~END;
  08 02 22 97 38 15 00 40 00 75 04 05 07 78 52 12 50 77 91 08
  49 49 99 40 17 81 18 57 60 87 17 40 98 43 69 48 04 56 62 00
  81 49 31 73 55 79 14 29 93 71 40 67 53 88 30 03 49 13 36 65
  52 70 95 23 04 60 11 42 69 24 68 56 01 32 56 71 37 02 36 91
  22 31 16 71 51 67 63 89 41 92 36 54 22 40 40 28 66 33 13 80
  24 47 32 60 99 03 45 02 44 75 33 53 78 36 84 20 35 17 12 50
  32 98 81 28 64 23 67 10 26 38 40 67 59 54 70 66 18 38 64 70
  67 26 20 68 02 62 12 20 95 63 94 39 63 08 40 91 66 49 94 21
  24 55 58 05 66 73 99 26 97 17 78 78 96 83 14 88 34 89 63 72
  21 36 23 09 75 00 76 44 20 45 35 14 00 61 33 97 34 31 33 95
  78 17 53 28 22 75 31 67 15 94 03 80 04 62 16 14 09 53 56 92
  16 39 05 42 96 35 31 47 55 58 88 24 00 17 54 24 36 29 85 57
  86 56 00 48 35 71 89 07 05 44 44 37 44 60 21 58 51 54 17 58
  19 80 81 68 05 94 47 69 28 73 92 13 86 52 17 77 04 89 55 40
  04 52 08 83 97 35 99 16 07 97 57 32 16 26 26 79 33 27 98 66
  88 36 68 87 57 62 20 72 03 46 33 67 46 55 12 32 63 93 53 69
  04 42 16 73 38 25 39 11 24 94 72 18 08 46 29 32 40 62 76 36
  20 69 36 41 72 30 23 88 34 62 99 69 82 67 59 85 74 04 36 16
  20 73 35 29 78 31 90 01 74 31 49 71 48 86 81 16 23 57 05 54
  01 70 54 71 83 51 54 69 16 92 33 48 61 43 52 01 89 19 67 48
  END

my(@m,@mt);
push @m, [ split /\s+/, s/\b0//gr ] for split "\n", $input;
for my $j (0..$#{$m[0]}) { push @mt, [ map $_->[$j], @m ] } # transpose

sub max_products {
    my($terms,@matrix) = @_;
    my @products;
    my $columns = 1 + $#{$matrix[0]};
    for my $row (@matrix) {
        map { push @products, reduce { $a * $b } @$row[ $_ .. $_+$terms-1 ] } 0 .. $columns-$terms;
    }
    max @products
}

say "Largest product of $_ adjacent elements: " . max max_products($_,@m), max_products($_,@mt) for 1..6;

Output:

Largest product of 1 adjacent elements: 99
Largest product of 2 adjacent elements: 9215
Largest product of 3 adjacent elements: 776776
Largest product of 4 adjacent elements: 51267216
Largest product of 5 adjacent elements: 2326829868
Largest product of 6 adjacent elements: 188210512710

Phix

with javascript_semantics
function splint(string s) 
    return apply(split(s),to_integer)
end function
constant grid = apply(split("""
08 02 22 97 38 15 00 40 00 75 04 05 07 78 52 12 50 77 91 08
49 49 99 40 17 81 18 57 60 87 17 40 98 43 69 48 04 56 62 00
81 49 31 73 55 79 14 29 93 71 40 67 53 88 30 03 49 13 36 65
52 70 95 23 04 60 11 42 69 24 68 56 01 32 56 71 37 02 36 91
22 31 16 71 51 67 63 89 41 92 36 54 22 40 40 28 66 33 13 80
24 47 32 60 99 03 45 02 44 75 33 53 78 36 84 20 35 17 12 50
32 98 81 28 64 23 67 10 26 38 40 67 59 54 70 66 18 38 64 70
67 26 20 68 02 62 12 20 95 63 94 39 63 08 40 91 66 49 94 21
24 55 58 05 66 73 99 26 97 17 78 78 96 83 14 88 34 89 63 72
21 36 23 09 75 00 76 44 20 45 35 14 00 61 33 97 34 31 33 95
78 17 53 28 22 75 31 67 15 94 03 80 04 62 16 14 09 53 56 92
16 39 05 42 96 35 31 47 55 58 88 24 00 17 54 24 36 29 85 57
86 56 00 48 35 71 89 07 05 44 44 37 44 60 21 58 51 54 17 58
19 80 81 68 05 94 47 69 28 73 92 13 86 52 17 77 04 89 55 40
04 52 08 83 97 35 99 16 07 97 57 32 16 26 26 79 33 27 98 66
88 36 68 87 57 62 20 72 03 46 33 67 46 55 12 32 63 93 53 69
04 42 16 73 38 25 39 11 24 94 72 18 08 46 29 32 40 62 76 36
20 69 36 41 72 30 23 88 34 62 99 69 82 67 59 85 74 04 36 16
20 73 35 29 78 31 90 01 74 31 49 71 48 86 81 16 23 57 05 54
01 70 54 71 83 51 54 69 16 92 33 48 61 43 52 01 89 19 67 48
""","\n"),splint)
function gridmax(integer len)
    sequence gmax = {0,"???",0,0}
    integer height = length(grid), 
            width = length(grid[1])
    atom prod
    for row=1 to height do
        integer rmax = row+len-1
        for col=1 to width do
            integer cmax = col+len-1
            if cmax<=width then
                prod = product(grid[row][col..cmax])
                gmax = max(gmax,{prod,"row",row,col})
            end if
            if rmax<=height then
                prod = product(vslice(grid,col)[row..rmax])
                gmax = max(gmax,{prod,"column",row,col})
            end if
        end for
    end for
    return gmax
end function
for i=1 to 6 do
    printf(1,"The largest product of length %d is %,d in %s starting at %d,%d\n",i&gridmax(i))
end for

Output:

The largest product of length 1 is 99 in row starting at 18,11
The largest product of length 2 is 9,215 in column starting at 8,9
The largest product of length 3 is 776,776 in column starting at 8,16
The largest product of length 4 is 51,267,216 in column starting at 7,16
The largest product of length 5 is 2,326,829,868 in row starting at 18,10
The largest product of length 6 is 188,210,512,710 in row starting at 18,11

PHP

Translation of: C

<?php
  // Largest product in a grid
  const PROD_LEN = 4;
  const GRID_SIZE = 20;
  const J_MAX = GRID_SIZE - PROD_LEN;

  $grid =
    array(
      array( 8,  2, 22, 97, 38, 15,  0, 40,  0, 75,  4,  5,  7, 78, 52, 12, 50, 77, 91,  8), 
      array(49, 49, 99, 40, 17, 81, 18, 57, 60, 87, 17, 40, 98, 43, 69, 48,  4, 56, 62,  0), 
      array(81, 49, 31, 73, 55, 79, 14, 29, 93, 71, 40, 67, 53, 88, 30,  3, 49, 13, 36, 65), 
      array(52, 70, 95, 23,  4, 60, 11, 42, 69, 24, 68, 56,  1, 32, 56, 71, 37,  2, 36, 91), 
      array(22, 31, 16, 71, 51, 67, 63, 89, 41, 92, 36, 54, 22, 40, 40, 28, 66, 33, 13, 80), 
      array(24, 47, 32, 60, 99,  3, 45,  2, 44, 75, 33, 53, 78, 36, 84, 20, 35, 17, 12, 50), 
      array(32, 98, 81, 28, 64, 23, 67, 10, 26, 38, 40, 67, 59, 54, 70, 66, 18, 38, 64, 70), 
      array(67, 26, 20, 68,  2, 62, 12, 20, 95, 63, 94, 39, 63,  8, 40, 91, 66, 49, 94, 21), 
      array(24, 55, 58,  5, 66, 73, 99, 26, 97, 17, 78, 78, 96, 83, 14, 88, 34, 89, 63, 72), 
      array(21, 36, 23,  9, 75,  0, 76, 44, 20, 45, 35, 14,  0, 61, 33, 97, 34, 31, 33, 95), 
      array(78, 17, 53, 28, 22, 75, 31, 67, 15, 94,  3, 80,  4, 62, 16, 14,  9, 53, 56, 92), 
      array(16, 39,  5, 42, 96, 35, 31, 47, 55, 58, 88, 24,  0, 17, 54, 24, 36, 29, 85, 57), 
      array(86, 56,  0, 48, 35, 71, 89,  7,  5, 44, 44, 37, 44, 60, 21, 58, 51, 54, 17, 58), 
      array(19, 80, 81, 68,  5, 94, 47, 69, 28, 73, 92, 13, 86, 52, 17, 77,  4, 89, 55, 40), 
      array( 4, 52,  8, 83, 97, 35, 99, 16,  7, 97, 57, 32, 16, 26, 26, 79, 33, 27, 98, 66), 
      array(88, 36, 68, 87, 57, 62, 20, 72,  3, 46, 33, 67, 46, 55, 12, 32, 63, 93, 53, 69), 
      array( 4, 42, 16, 73, 38, 25, 39, 11, 24, 94, 72, 18,  8, 46, 29, 32, 40, 62, 76, 36), 
      array(20, 69, 36, 41, 72, 30, 23, 88, 34, 62, 99, 69, 82, 67, 59, 85, 74,  4, 36, 16), 
      array(20, 73, 35, 29, 78, 31, 90,  1, 74, 31, 49, 71, 48, 86, 81, 16, 23, 57,  5, 54), 
      array( 1, 70, 54, 71, 83, 51, 54, 69, 16, 92, 33, 48, 61, 43, 52,  1, 89, 19, 67, 48)
    );
  
  $max = 0;
  for ($j = 0; $j < GRID_SIZE; $j++)
    for ($i = 0; $i <= J_MAX; $i++)
      for ($k = $i, $prod = 1, $k_max = PROD_LEN + $i - 1; $k <= $k_max; $k++) { 
        $prod *= $grid[$j][$k];
        if ($prod > $max) 
          $max = $prod;
      }
  for ($j = 0; $j <= J_MAX; $j++)
    for ($i = 0; $i < GRID_SIZE; $i++)
      for ($k = $j, $prod = 1, $k_max = PROD_LEN + $j - 1; $k <= $k_max; $k++) { 
        $prod *= $grid[$k][$i];
        if ($prod > $max) 
          $max = $prod;
      }
  echo($max);
  echo("\n");
?>

Output:

51267216

Python

Translation of: Julia

""" Rosetta code task: Largest_product_in_a_grid """

from math import prod

def maxproduct(mat, length):
    """ find the largest product of len length horizontal or vertical length in matrix """
    nrow, ncol = len(mat), len(mat[0])
    maxprod, maxrow, maxcol, arr = 0, [0, 0], [0, 0], [0]
    for row in range(nrow):
        for col in range(ncol):
            row2, col2 = row + length, col + length
            if row < nrow - length:
                array = [r[col] for r in mat[row:row2]]
                pro = prod(array)
                if pro > maxprod:
                    maxprod, maxrow, maxcol, arr = pro, [row, row2], col, array
            if col < ncol - length:
                pro = prod(mat[row][col:col2])
                if pro > maxprod:
                    maxprod, maxrow, maxcol, arr = pro, row, [col, col2], mat[row][col:col2]

    print(f"The max {length}-product is {maxprod}, product of {arr} at row {maxrow}, col {maxcol}.")

MATRIX = [
    [ 8,  2, 22, 97, 38, 15,  0, 40,  0, 75,  4,  5,  7, 78, 52, 12, 50, 77, 91,  8],
    [49, 49, 99, 40, 17, 81, 18, 57, 60, 87, 17, 40, 98, 43, 69, 48,  4, 56, 62,  0],
    [81, 49, 31, 73, 55, 79, 14, 29, 93, 71, 40, 67, 53, 88, 30,  3, 49, 13, 36, 65],
    [52, 70, 95, 23,  4, 60, 11, 42, 69, 24, 68, 56,  1, 32, 56, 71, 37,  2, 36, 91],
    [22, 31, 16, 71, 51, 67, 63, 89, 41, 92, 36, 54, 22, 40, 40, 28, 66, 33, 13, 80],
    [24, 47, 32, 60, 99,  3, 45,  2, 44, 75, 33, 53, 78, 36, 84, 20, 35, 17, 12, 50],
    [32, 98, 81, 28, 64, 23, 67, 10, 26, 38, 40, 67, 59, 54, 70, 66, 18, 38, 64, 70],
    [67, 26, 20, 68,  2, 62, 12, 20, 95, 63, 94, 39, 63,  8, 40, 91, 66, 49, 94, 21],
    [24, 55, 58,  5, 66, 73, 99, 26, 97, 17, 78, 78, 96, 83, 14, 88, 34, 89, 63, 72],
    [21, 36, 23,  9, 75,  0, 76, 44, 20, 45, 35, 14,  0, 61, 33, 97, 34, 31, 33, 95],
    [78, 17, 53, 28, 22, 75, 31, 67, 15, 94,  3, 80,  4, 62, 16, 14,  9, 53, 56, 92],
    [16, 39,  5, 42, 96, 35, 31, 47, 55, 58, 88, 24,  0, 17, 54, 24, 36, 29, 85, 57],
    [86, 56,  0, 48, 35, 71, 89,  7,  5, 44, 44, 37, 44, 60, 21, 58, 51, 54, 17, 58],
    [19, 80, 81, 68,  5, 94, 47, 69, 28, 73, 92, 13, 86, 52, 17, 77,  4, 89, 55, 40],
    [ 4, 52,  8, 83, 97, 35, 99, 16,  7, 97, 57, 32, 16, 26, 26, 79, 33, 27, 98, 66],
    [88, 36, 68, 87, 57, 62, 20, 72,  3, 46, 33, 67, 46, 55, 12, 32, 63, 93, 53, 69],
    [ 4, 42, 16, 73, 38, 25, 39, 11, 24, 94, 72, 18,  8, 46, 29, 32, 40, 62, 76, 36],
    [20, 69, 36, 41, 72, 30, 23, 88, 34, 62, 99, 69, 82, 67, 59, 85, 74,  4, 36, 16],
    [20, 73, 35, 29, 78, 31, 90,  1, 74, 31, 49, 71, 48, 86, 81, 16, 23, 57,  5, 54],
    [ 1, 70, 54, 71, 83, 51, 54, 69, 16, 92, 33, 48, 61, 43, 52,  1, 89, 19, 67, 48]
]

for n in range(2, 6):
    maxproduct(MATRIX, n)

Output:

The max 2-product is 9215, product of [95, 97] at row [7, 9], col 8.
The max 3-product is 776776, product of [91, 88, 97] at row [7, 10], col 15.
The max 4-product is 51267216, product of [66, 91, 88, 97] at row [6, 10], col 15.
The max 5-product is 2326829868, product of [62, 99, 69, 82, 67] at row 17, col [9, 14].

Quackery

transpose is defined at Matrix transposition#Quackery.

   [ 1 swap witheach * ]   is product ( [ --> n )

   [ 4 split
     over product
     unrot witheach
       [  join behead drop
          tuck product
          max swap ]
     drop ]                is 4*max   ( [ --> n )

  ' [ [ 08 02 22 97 38 15 00 40 00 75 04 05 07 78 52 12 50 77 91 08 ]
      [ 49 49 99 40 17 81 18 57 60 87 17 40 98 43 69 48 04 56 62 00 ]
      [ 81 49 31 73 55 79 14 29 93 71 40 67 53 88 30 03 49 13 36 65 ]
      [ 52 70 95 23 04 60 11 42 69 24 68 56 01 32 56 71 37 02 36 91 ]
      [ 22 31 16 71 51 67 63 89 41 92 36 54 22 40 40 28 66 33 13 80 ]
      [ 24 47 32 60 99 03 45 02 44 75 33 53 78 36 84 20 35 17 12 50 ]
      [ 32 98 81 28 64 23 67 10 26 38 40 67 59 54 70 66 18 38 64 70 ]
      [ 67 26 20 68 02 62 12 20 95 63 94 39 63 08 40 91 66 49 94 21 ]
      [ 24 55 58 05 66 73 99 26 97 17 78 78 96 83 14 88 34 89 63 72 ]
      [ 21 36 23 09 75 00 76 44 20 45 35 14 00 61 33 97 34 31 33 95 ]
      [ 78 17 53 28 22 75 31 67 15 94 03 80 04 62 16 14 09 53 56 92 ]
      [ 16 39 05 42 96 35 31 47 55 58 88 24 00 17 54 24 36 29 85 57 ]
      [ 86 56 00 48 35 71 89 07 05 44 44 37 44 60 21 58 51 54 17 58 ]
      [ 19 80 81 68 05 94 47 69 28 73 92 13 86 52 17 77 04 89 55 40 ]
      [ 04 52 08 83 97 35 99 16 07 97 57 32 16 26 26 79 33 27 98 66 ]
      [ 88 36 68 87 57 62 20 72 03 46 33 67 46 55 12 32 63 93 53 69 ]
      [ 04 42 16 73 38 25 39 11 24 94 72 18 08 46 29 32 40 62 76 36 ]
      [ 20 69 36 41 72 30 23 88 34 62 99 69 82 67 59 85 74 04 36 16 ]
      [ 20 73 35 29 78 31 90 01 74 31 49 71 48 86 81 16 23 57 05 54 ]
      [ 01 70 54 71 83 51 54 69 16 92 33 48 61 43 52 01 89 19 67 48 ] ]

   0 over
   witheach [ 4*max max ]
   swap transpose
   witheach [ 4*max max ]
   echo

Output:

51267216

Raku

General solution. No hard coded values. Works with any size matrix, configurable number of terms.

my @matrix = q:to/END/.lines».words;
  08 02 22 97 38 15 00 40 00 75 04 05 07 78 52 12 50 77 91 08
  49 49 99 40 17 81 18 57 60 87 17 40 98 43 69 48 04 56 62 00
  81 49 31 73 55 79 14 29 93 71 40 67 53 88 30 03 49 13 36 65
  52 70 95 23 04 60 11 42 69 24 68 56 01 32 56 71 37 02 36 91
  22 31 16 71 51 67 63 89 41 92 36 54 22 40 40 28 66 33 13 80
  24 47 32 60 99 03 45 02 44 75 33 53 78 36 84 20 35 17 12 50
  32 98 81 28 64 23 67 10 26 38 40 67 59 54 70 66 18 38 64 70
  67 26 20 68 02 62 12 20 95 63 94 39 63 08 40 91 66 49 94 21
  24 55 58 05 66 73 99 26 97 17 78 78 96 83 14 88 34 89 63 72
  21 36 23 09 75 00 76 44 20 45 35 14 00 61 33 97 34 31 33 95
  78 17 53 28 22 75 31 67 15 94 03 80 04 62 16 14 09 53 56 92
  16 39 05 42 96 35 31 47 55 58 88 24 00 17 54 24 36 29 85 57
  86 56 00 48 35 71 89 07 05 44 44 37 44 60 21 58 51 54 17 58
  19 80 81 68 05 94 47 69 28 73 92 13 86 52 17 77 04 89 55 40
  04 52 08 83 97 35 99 16 07 97 57 32 16 26 26 79 33 27 98 66
  88 36 68 87 57 62 20 72 03 46 33 67 46 55 12 32 63 93 53 69
  04 42 16 73 38 25 39 11 24 94 72 18 08 46 29 32 40 62 76 36
  20 69 36 41 72 30 23 88 34 62 99 69 82 67 59 85 74 04 36 16
  20 73 35 29 78 31 90 01 74 31 49 71 48 86 81 16 23 57 05 54
  01 70 54 71 83 51 54 69 16 92 33 48 61 43 52 01 89 19 67 48 
END

my $terms = 4;

say "Largest product of $terms adjacent elements: " ~ max flat (^@matrix).map: {
    @matrix.rotor($terms => -$terms+1).flat»[$_].batch($terms)».reduce(&[*]), # vertical
    @matrix[$_].rotor($terms => -$terms+1)».reduce(&[*]);                     # horizontal
}

Output:

Largest product of 4 adjacent elements: 51267216

REXX

/* REXX */
Call mk_a 1,08,02,22,97,38,15,00,40,00,75,04,05,07,78,52,12,50,77,91,08
Call mk_a 2,49,49,99,40,17,81,18,57,60,87,17,40,98,43,69,48,04,56,62,00
Call mk_a 3,81,49,31,73,55,79,14,29,93,71,40,67,53,88,30,03,49,13,36,65
Call mk_a 4,52,70,95,23,04,60,11,42,69,24,68,56,01,32,56,71,37,02,36,91
Call mk_a 5,22,31,16,71,51,67,63,89,41,92,36,54,22,40,40,28,66,33,13,80
Call mk_a 6,24,47,32,60,99,03,45,02,44,75,33,53,78,36,84,20,35,17,12,50
Call mk_a 7,32,98,81,28,64,23,67,10,26,38,40,67,59,54,70,66,18,38,64,70
Call mk_a 8,67,26,20,68,02,62,12,20,95,63,94,39,63,08,40,91,66,49,94,21
Call mk_a 9,24,55,58,05,66,73,99,26,97,17,78,78,96,83,14,88,34,89,63,72
Call mk_a 10,21,36,23,09,75,00,76,44,20,45,35,14,00,61,33,97,34,31,33,95
Call mk_a 11,78,17,53,28,22,75,31,67,15,94,03,80,04,62,16,14,09,53,56,92
Call mk_a 12,16,39,05,42,96,35,31,47,55,58,88,24,00,17,54,24,36,29,85,57
Call mk_a 13,86,56,00,48,35,71,89,07,05,44,44,37,44,60,21,58,51,54,17,58
Call mk_a 14,19,80,81,68,05,94,47,69,28,73,92,13,86,52,17,77,04,89,55,40
Call mk_a 15,04,52,08,83,97,35,99,16,07,97,57,32,16,26,26,79,33,27,98,66
Call mk_a 16,88,36,68,87,57,62,20,72,03,46,33,67,46,55,12,32,63,93,53,69
Call mk_a 17,04,42,16,73,38,25,39,11,24,94,72,18,08,46,29,32,40,62,76,36
Call mk_a 18,20,69,36,41,72,30,23,88,34,62,99,69,82,67,59,85,74,04,36,16
Call mk_a 19,20,73,35,29,78,31,90,01,74,31,49,71,48,86,81,16,23,57,05,54
Call mk_a 20,01,70,54,71,83,51,54,69,16,92,33,48,61,43,52,01,89,19,67,48
max=0
Do row=1 To 20
  Do col=1 To 17
    Parse Value (col+1) (col+2) (col+3) With col1 col2 col3
    prod=a.row.col*a.row.col1*a.row.col2*a.row.col3
    If prod>max Then Do
      max=prod
      rc=row col
      l=a.row.col'*'a.row.col1'*'a.row.col2'*'a.row.col3'='prod
      End
    End
  End
Parse Var rc row col
Say 'Maximum in row' row 'columns' col '...' (col+3) ':' ö
Do col=1 to 20
  Do row=1 To 17
    Parse Value (row+1) (row+2) (row+3) With row1 row2 row3
    prod=a.row.col*a.row1.col*a.row2.col*a.row3.col
    If prod>max Then Do
      max=prod
      rc=row col
      l=a.row.col'*'a.row1.col'*'a.row2.col'*'a.row3.col'='prod
      End
    End
  End
Parse Var rc row col
Say 'Maximum in row' row 'columns' col '...' (col+3) ':' l

mk_a:
row=arg(1)
Do col=1 To 20
  a.row.col=arg(col+1)
  End
Return

Output:

 Maximum in row 9 columns 11 ... 14 : 78*78*96*83=48477312
 Maximum in column 16 rows 7 ... 10 : 66*91*88*97=51267216

Ring

see "working..." + nl
see "Largest product is:" + nl

Grid = [[08, 02, 22, 97, 38, 15, 00, 40, 00, 75, 04, 05, 07, 78, 52, 12, 50, 77, 91, 08],
        [49, 49, 99, 40, 17, 81, 18, 57, 60, 87, 17, 40, 98, 43, 69, 48, 04, 56, 62, 00],
        [81, 49, 31, 73, 55, 79, 14, 29, 93, 71, 40, 67, 53, 88, 30, 03, 49, 13, 36, 65],
        [52, 70, 95, 23, 04, 60, 11, 42, 69, 24, 68, 56, 01, 32, 56, 71, 37, 02, 36, 91],
        [22, 31, 16, 71, 51, 67, 63, 89, 41, 92, 36, 54, 22, 40, 40, 28, 66, 33, 13, 80],
        [24, 47, 32, 60, 99, 03, 45, 02, 44, 75, 33, 53, 78, 36, 84, 20, 35, 17, 12, 50],
        [32, 98, 81, 28, 64, 23, 67, 10, 26, 38, 40, 67, 59, 54, 70, 66, 18, 38, 64, 70],
        [67, 26, 20, 68, 02, 62, 12, 20, 95, 63, 94, 39, 63, 08, 40, 91, 66, 49, 94, 21],
        [24, 55, 58, 05, 66, 73, 99, 26, 97, 17, 78, 78, 96, 83, 14, 88, 34, 89, 63, 72],
        [21, 36, 23, 09, 75, 00, 76, 44, 20, 45, 35, 14, 00, 61, 33, 97, 34, 31, 33, 95],
        [78, 17, 53, 28, 22, 75, 31, 67, 15, 94, 03, 80, 04, 62, 16, 14, 09, 53, 56, 92],
        [16, 39, 05, 42, 96, 35, 31, 47, 55, 58, 88, 24, 00, 17, 54, 24, 36, 29, 85, 57],
        [86, 56, 00, 48, 35, 71, 89, 07, 05, 44, 44, 37, 44, 60, 21, 58, 51, 54, 17, 58],
        [19, 80, 81, 68, 05, 94, 47, 69, 28, 73, 92, 13, 86, 52, 17, 77, 04, 89, 55, 40],
        [04, 52, 08, 83, 97, 35, 99, 16, 07, 97, 57, 32, 16, 26, 26, 79, 33, 27, 98, 66],
        [88, 36, 68, 87, 57, 62, 20, 72, 03, 46, 33, 67, 46, 55, 12, 32, 63, 93, 53, 69],
        [04, 42, 16, 73, 38, 25, 39, 11, 24, 94, 72, 18, 08, 46, 29, 32, 40, 62, 76, 36],
        [20, 69, 36, 41, 72, 30, 23, 88, 34, 62, 99, 69, 82, 67, 59, 85, 74, 04, 36, 16],
        [20, 73, 35, 29, 78, 31, 90, 01, 74, 31, 49, 71, 48, 86, 81, 16, 23, 57, 05, 54],
        [01, 70, 54, 71, 83, 51, 54, 69, 16, 92, 33, 48, 61, 43, 52, 01, 89, 19, 67, 48]]

Index = []
resTemp = []
prodNew = 0

for n = 1 to 17
    prod = 0
    for m = 1 to 20
        prod = Grid[n][m] * Grid[n+1][m] * Grid[n+2][m] * Grid[n+3][m]
        if prod > prodNew
           prodNew = prod 
           res = 1000*Grid[n][m] + 100*Grid[n+1][m] + 10*Grid[n+2][m] + Grid[n+3][m]
           resTemp = []
           Index = []
           add(Index,[n,m])
           add(Index,[n+1,m])
           add(Index,[n+2,m])
           add(Index,[n+3,m])           
           add(resTemp,Grid[n][m])
           add(resTemp,Grid[n+1][m])
           add(resTemp,Grid[n+2][m])
           add(resTemp,Grid[n+3][m])
        ok
    next
next

for n = 20 to 1 step -1
    prod = 0
    for m = 1 to 17
        prod = Grid[n][m] * Grid[n][m+1] * Grid[n][m+2] * Grid[n][m+3]
        if prod > prodNew
           prodNew = prod 
           res = 1000*Grid[n][m] + 100*Grid[n][m+1] + 10*Grid[n][m+2] + Grid[n][m+3]
           resTemp = []
           Index = []
           add(Index,[n,m])
           add(Index,[n,m+1])
           add(Index,[n,m+2])
           add(Index,[n,m+3])
           resTemp = []
           add(resTemp,Grid[n][m])
           add(resTemp,Grid[n][m+1])
           add(resTemp,Grid[n+2][m+2])
           add(resTemp,Grid[n][m+3])
        ok
    next
next

for n = 1 to len(resTemp)-1
    see "" + resTemp[n] + " * "
next
see "" + resTemp[len(resTemp)] + " = " + prodNew + nl

see "Indices = "
for n = 1 to len(Index)
    see "(" + Index[n][1] + "," + Index[n][2] + ")"
next

see nl + "done..." + nl

Output:

working...
Largest product is:
66 * 91 * 88 * 97 = 51267216
Indices = (7,16)(8,16)(9,16)(10,16)
done...

Ruby

gridstr =
"08 02 22 97 38 15 00 40 00 75 04 05 07 78 52 12 50 77 91 08
49 49 99 40 17 81 18 57 60 87 17 40 98 43 69 48 04 56 62 00
81 49 31 73 55 79 14 29 93 71 40 67 53 88 30 03 49 13 36 65
52 70 95 23 04 60 11 42 69 24 68 56 01 32 56 71 37 02 36 91
22 31 16 71 51 67 63 89 41 92 36 54 22 40 40 28 66 33 13 80
24 47 32 60 99 03 45 02 44 75 33 53 78 36 84 20 35 17 12 50
32 98 81 28 64 23 67 10 26 38 40 67 59 54 70 66 18 38 64 70
67 26 20 68 02 62 12 20 95 63 94 39 63 08 40 91 66 49 94 21
24 55 58 05 66 73 99 26 97 17 78 78 96 83 14 88 34 89 63 72
21 36 23 09 75 00 76 44 20 45 35 14 00 61 33 97 34 31 33 95
78 17 53 28 22 75 31 67 15 94 03 80 04 62 16 14 09 53 56 92
16 39 05 42 96 35 31 47 55 58 88 24 00 17 54 24 36 29 85 57
86 56 00 48 35 71 89 07 05 44 44 37 44 60 21 58 51 54 17 58
19 80 81 68 05 94 47 69 28 73 92 13 86 52 17 77 04 89 55 40
04 52 08 83 97 35 99 16 07 97 57 32 16 26 26 79 33 27 98 66
88 36 68 87 57 62 20 72 03 46 33 67 46 55 12 32 63 93 53 69
04 42 16 73 38 25 39 11 24 94 72 18 08 46 29 32 40 62 76 36
20 69 36 41 72 30 23 88 34 62 99 69 82 67 59 85 74 04 36 16
20 73 35 29 78 31 90 01 74 31 49 71 48 86 81 16 23 57 05 54
01 70 54 71 83 51 54 69 16 92 33 48 61 43 52 01 89 19 67 48"

grid = gridstr.lines.map{|line| line.split.map(&:to_i) }
hor_ver = grid.each + grid.transpose.each
puts hor_ver.map{|line| line.each_cons(4).map{|slice| slice.inject(&:*) }.max}.max

Output:

51267216

Sidef

var text = <<'EOT'
08 02 22 97 38 15 00 40 00 75 04 05 07 78 52 12 50 77 91 08
49 49 99 40 17 81 18 57 60 87 17 40 98 43 69 48 04 56 62 00
81 49 31 73 55 79 14 29 93 71 40 67 53 88 30 03 49 13 36 65
52 70 95 23 04 60 11 42 69 24 68 56 01 32 56 71 37 02 36 91
22 31 16 71 51 67 63 89 41 92 36 54 22 40 40 28 66 33 13 80
24 47 32 60 99 03 45 02 44 75 33 53 78 36 84 20 35 17 12 50
32 98 81 28 64 23 67 10 26 38 40 67 59 54 70 66 18 38 64 70
67 26 20 68 02 62 12 20 95 63 94 39 63 08 40 91 66 49 94 21
24 55 58 05 66 73 99 26 97 17 78 78 96 83 14 88 34 89 63 72
21 36 23 09 75 00 76 44 20 45 35 14 00 61 33 97 34 31 33 95
78 17 53 28 22 75 31 67 15 94 03 80 04 62 16 14 09 53 56 92
16 39 05 42 96 35 31 47 55 58 88 24 00 17 54 24 36 29 85 57
86 56 00 48 35 71 89 07 05 44 44 37 44 60 21 58 51 54 17 58
19 80 81 68 05 94 47 69 28 73 92 13 86 52 17 77 04 89 55 40
04 52 08 83 97 35 99 16 07 97 57 32 16 26 26 79 33 27 98 66
88 36 68 87 57 62 20 72 03 46 33 67 46 55 12 32 63 93 53 69
04 42 16 73 38 25 39 11 24 94 72 18 08 46 29 32 40 62 76 36
20 69 36 41 72 30 23 88 34 62 99 69 82 67 59 85 74 04 36 16
20 73 35 29 78 31 90 01 74 31 49 71 48 86 81 16 23 57 05 54
01 70 54 71 83 51 54 69 16 92 33 48 61 43 52 01 89 19 67 48
EOT

func horizontal(N, i, j, matrix) {
    N.of {|k| matrix[i][j+k] }
}

func diagonal(N, i, j, matrix) {
    N.of {|k| matrix[i+k][j+k] }
}

var matrix = Matrix(text.lines.map{ .nums }...)

var reversed_matrix   = matrix.horizontal_flip
var transposed_matrix = matrix.transpose

define (
    CHECK_DIAGONALS = false   # true to also check diagonals
)

const e = matrix.end

for N in (1..6) {

    var products = gather {
        for i in (0..e), j in (0..e) {

            (j+N < e) || next

            # Horizontal and vertical
            take(horizontal(N, i, j, matrix))
            take(horizontal(N, i, j, transposed_matrix))

            CHECK_DIAGONALS || next
            (i+N < e)       || next

            # Left-to-right and right-to-left diagonals
            take(diagonal(N, i, j, matrix))
            take(diagonal(N, i, j, reversed_matrix))
        }
    }

    var nums = products.max_by { .prod }
    say "Largest product of #{N} adjacent elements: prod(#{nums}) = #{nums.prod}"
}

Output:

Largest product of 1 adjacent elements: prod([99]) = 99
Largest product of 2 adjacent elements: prod([95, 97]) = 9215
Largest product of 3 adjacent elements: prod([91, 88, 97]) = 776776
Largest product of 4 adjacent elements: prod([66, 91, 88, 97]) = 51267216
Largest product of 5 adjacent elements: prod([62, 99, 69, 82, 67]) = 2326829868
Largest product of 6 adjacent elements: prod([99, 69, 82, 67, 59, 85]) = 188210512710

Wren

Library: Wren-fmt

import "./fmt" for Fmt

var grid = [
    [08, 02, 22, 97, 38, 15, 00, 40, 00, 75, 04, 05, 07, 78, 52, 12, 50, 77, 91, 08],
    [49, 49, 99, 40, 17, 81, 18, 57, 60, 87, 17, 40, 98, 43, 69, 48, 04, 56, 62, 00],
    [81, 49, 31, 73, 55, 79, 14, 29, 93, 71, 40, 67, 53, 88, 30, 03, 49, 13, 36, 65],
    [52, 70, 95, 23, 04, 60, 11, 42, 69, 24, 68, 56, 01, 32, 56, 71, 37, 02, 36, 91],
    [22, 31, 16, 71, 51, 67, 63, 89, 41, 92, 36, 54, 22, 40, 40, 28, 66, 33, 13, 80],
    [24, 47, 32, 60, 99, 03, 45, 02, 44, 75, 33, 53, 78, 36, 84, 20, 35, 17, 12, 50],
    [32, 98, 81, 28, 64, 23, 67, 10, 26, 38, 40, 67, 59, 54, 70, 66, 18, 38, 64, 70],
    [67, 26, 20, 68, 02, 62, 12, 20, 95, 63, 94, 39, 63, 08, 40, 91, 66, 49, 94, 21],
    [24, 55, 58, 05, 66, 73, 99, 26, 97, 17, 78, 78, 96, 83, 14, 88, 34, 89, 63, 72],
    [21, 36, 23, 09, 75, 00, 76, 44, 20, 45, 35, 14, 00, 61, 33, 97, 34, 31, 33, 95],
    [78, 17, 53, 28, 22, 75, 31, 67, 15, 94, 03, 80, 04, 62, 16, 14, 09, 53, 56, 92],
    [16, 39, 05, 42, 96, 35, 31, 47, 55, 58, 88, 24, 00, 17, 54, 24, 36, 29, 85, 57],
    [86, 56, 00, 48, 35, 71, 89, 07, 05, 44, 44, 37, 44, 60, 21, 58, 51, 54, 17, 58],
    [19, 80, 81, 68, 05, 94, 47, 69, 28, 73, 92, 13, 86, 52, 17, 77, 04, 89, 55, 40],
    [04, 52, 08, 83, 97, 35, 99, 16, 07, 97, 57, 32, 16, 26, 26, 79, 33, 27, 98, 66],
    [88, 36, 68, 87, 57, 62, 20, 72, 03, 46, 33, 67, 46, 55, 12, 32, 63, 93, 53, 69],
    [04, 42, 16, 73, 38, 25, 39, 11, 24, 94, 72, 18, 08, 46, 29, 32, 40, 62, 76, 36],
    [20, 69, 36, 41, 72, 30, 23, 88, 34, 62, 99, 69, 82, 67, 59, 85, 74, 04, 36, 16],
    [20, 73, 35, 29, 78, 31, 90, 01, 74, 31, 49, 71, 48, 86, 81, 16, 23, 57, 05, 54],
    [01, 70, 54, 71, 83, 51, 54, 69, 16, 92, 33, 48, 61, 43, 52, 01, 89, 19, 67, 48]
]

var maxProd = 0
var maxNums = [0, 0, 0, 0]
var maxR1 = 0
var maxR2 = 0
var maxC1 = 0
var maxC2 = 0
var h = grid.count
var w = grid[0].count

// right
for (r in 0...h) {
    for (c in 0..w-5) {
        var prod = 1
        for (i in c..c+3) prod = prod * grid[r][i]
        if (prod > maxProd) {
            maxProd = prod
            for (n in 0..3) maxNums[n] = grid[r][c+n]
            maxR1 = maxR2 = r
            maxC1 = c
            maxC2 = c + 3
        }
    }
}

// down
for (c in 0...w) {
    for (r in 0..h-5) {
        var prod = 1
        for (i in r..r+3) prod = prod * grid[i][c]
        if (prod > maxProd) {
            maxProd = prod
            for (n in 0..3) maxNums[n] = grid[r+n][c]
            maxR1 = r
            maxR2 = r + 3
            maxC1 = maxC2 = c
        }
    }
}

System.print("The greatest product of four adjacent numbers in the same direction (down or right) in the grid is:")
Fmt.print("  $s = $,d", maxNums.map{ |n| n.toString }.join(" x "), maxProd)
System.write("  at indices (one based): ")
for (r in maxR1..maxR2) {
    for (c in maxC1..maxC2) Fmt.write("($d, $d) ", r+1, c+1)
}
System.print()

Output:

The greatest product of four adjacent numbers in the same direction (down or right) in the grid is:
  66 x 91 x 88 x 97 = 51,267,216
  at indices (one based): (7, 16) (8, 16) (9, 16) (10, 16) 

XPL0

int     Grid, Max, Prod, I, J, K;
[Grid:=[[08,02,22,97,38,15,00,40,00,75,04,05,07,78,52,12,50,77,91,08],
        [49,49,99,40,17,81,18,57,60,87,17,40,98,43,69,48,04,56,62,00],
        [81,49,31,73,55,79,14,29,93,71,40,67,53,88,30,03,49,13,36,65],
        [52,70,95,23,04,60,11,42,69,24,68,56,01,32,56,71,37,02,36,91],
        [22,31,16,71,51,67,63,89,41,92,36,54,22,40,40,28,66,33,13,80],
        [24,47,32,60,99,03,45,02,44,75,33,53,78,36,84,20,35,17,12,50],
        [32,98,81,28,64,23,67,10,26,38,40,67,59,54,70,66,18,38,64,70],
        [67,26,20,68,02,62,12,20,95,63,94,39,63,08,40,91,66,49,94,21],
        [24,55,58,05,66,73,99,26,97,17,78,78,96,83,14,88,34,89,63,72],
        [21,36,23,09,75,00,76,44,20,45,35,14,00,61,33,97,34,31,33,95],
        [78,17,53,28,22,75,31,67,15,94,03,80,04,62,16,14,09,53,56,92],
        [16,39,05,42,96,35,31,47,55,58,88,24,00,17,54,24,36,29,85,57],
        [86,56,00,48,35,71,89,07,05,44,44,37,44,60,21,58,51,54,17,58],
        [19,80,81,68,05,94,47,69,28,73,92,13,86,52,17,77,04,89,55,40],
        [04,52,08,83,97,35,99,16,07,97,57,32,16,26,26,79,33,27,98,66],
        [88,36,68,87,57,62,20,72,03,46,33,67,46,55,12,32,63,93,53,69],
        [04,42,16,73,38,25,39,11,24,94,72,18,08,46,29,32,40,62,76,36],
        [20,69,36,41,72,30,23,88,34,62,99,69,82,67,59,85,74,04,36,16],
        [20,73,35,29,78,31,90,01,74,31,49,71,48,86,81,16,23,57,05,54],
        [01,70,54,71,83,51,54,69,16,92,33,48,61,43,52,01,89,19,67,48]];
Max:= 0;
for J:= 0 to 20-1 do
    for I:= 0 to 20-4 do
        [Prod:= 1;
        for K:= 0 to 4-1 do
            [Prod:= Prod * Grid(J,I+K);
            if Prod > Max then Max:= Prod;
            ];
        ];
for J:= 0 to 20-4 do
    for I:= 0 to 20-1 do
        [Prod:= 1;
        for K:= 0 to 4-1 do
            [Prod:= Prod * Grid(J+K,I);
            if Prod > Max then Max:= Prod;
            ];
        ];
IntOut(0, Max);
]

Output:

51267216