Sudoku: Difference between revisions

</pre>

=={{header|Picat}}==

Using constraint programming.

<lang picat>import util.

import cp.

main => go.

go =>

sudokus(Sudokus),

foreach([Comment,SudokuS] in Sudokus)

println(SudokuS),

println(Comment),

% Convert string to numbers and "." to _ (unknown)

Sudoku = [ [cond(S == '.',_,S.to_integer()) :

S in slice(SudokuS,(I*9)+1,(I+1)*9)] : I in 0..8],

print_board(Sudoku),

% Ensure unicity of the solution (check that it is a unique solution)

All = findall(Sudoku,sudoku(Sudoku)),

if All.length > 1 then

printf("Problem has %d solutions!\n", All.length)

end,

print("Solution:")

foreach(A in All)

print_board(A)

end,

nl

end,

nl.

sudoku(Board) =>

N = ceiling(sqrt(Board.len)),

N2 = N*N,

Vars = Board.vars(),

Vars :: 1..N2,

foreach(Row in Board) all_different(Row) end,

foreach(Column in transpose(Board)) all_different(Column) end,

foreach(I in 1..N..N2, J in 1..N..N2)

all_different([Board[I+K,J+L] : K in 0..N-1, L in 0..N-1])

end,

solve([ffd,inout], Vars).

print_board(Board) =>

N = Board.length,

foreach(I in 1..N)

foreach(J in 1..N)

X = Board[I,J],

if var(X) then printf(" _") else printf(" %w", X) end

end,

nl

end,

nl.

% (Problems from the Groovy implementation)

sudokus(Sudokus) => Sudokus =

[

"819..5.....2...75..371.4.6.4..59.1..7..3.8..2..3.62..7.5.7.921..64...9.....2..438",

"53..247....2...8..1..7.39.2..8.72.49.2.98..7.79.....8.....3.5.696..1.3...5.69..1.",

"..3.2.6..9..3.5..1..18.64....81.29..7.......8..67.82....26.95..8..2.3..9..5.1.3..",

"394..267....3..4..5..69..2..45...9..6.......7..7...58..1..67..8..9..8....264..735",

"97.3...6..6.75.........8.5.......67.....3.....539..2..7...25.....2.1...8.4...73..",

"4......6.5...8.9..3....1....2.7....1.9.....4.8....3.5....2....7..6.5...8.1......6",

"85...24..72......9..4.........1.7..23.5...9...4...........8..7..17..........36.4.",

"..1..5.7.92.6.......8...6...9..2.4.1.........3.4.8..9...7...3.......7.69.1.8..7..",

".9...4..7.....79..8........4.58.....3.......2.....97.6........4..35.....2..6...8.",

"12.3....435....1....4........54..2..6...7.........8.9...31..5.......9.7.....6...8",

"9..2..5...4..6..3...3.....6...9..2......5..8...7..4..37.....1...5..2..4...1..6..9",

"1....7.9..3..2...8..96..5....53..9...1..8...26....4...3......1..4......7..7...3..",

"12.4..3..3...1..5...6...1..7...9.....4.6.3.....3..2...5...8.7....7.....5.......98",

"..............3.85..1.2.......5.7.....4...1...9.......5......73..2.1........4...9",

".......39.....1..5..3.5.8....8.9...6.7...2...1..4.......9.8..5..2....6..4..7.....",

"....839..1......3...4....7..42.3....6.......4....7..1..2........8...92.....25...6",

"..3......4...8..36..8...1...4..6..73...9..........2..5..4.7..686........7..6..5.."

].

</lang>

Output. All problems are solved (and proved/checked for unicity) in 0.043s.

<pre>

819..5.....2...75..371.4.6.4..59.1..7..3.8..2..3.62..7.5.7.921..64...9.....2..438

8 1 9 _ _ 5 _ _ _

_ _ 2 _ _ _ 7 5 _

_ 3 7 1 _ 4 _ 6 _

4 _ _ 5 9 _ 1 _ _

7 _ _ 3 _ 8 _ _ 2

_ _ 3 _ 6 2 _ _ 7

_ 5 _ 7 _ 9 2 1 _

_ 6 4 _ _ _ 9 _ _

_ _ _ 2 _ _ 4 3 8

Solution:

8 1 9 6 7 5 3 2 4

6 4 2 9 8 3 7 5 1

5 3 7 1 2 4 8 6 9

4 2 6 5 9 7 1 8 3

7 9 5 3 1 8 6 4 2

1 8 3 4 6 2 5 9 7

3 5 8 7 4 9 2 1 6

2 6 4 8 3 1 9 7 5

9 7 1 2 5 6 4 3 8

...