Multiplication tables
Produce a formatted 12×12 multiplication table of the kind memorised by rote when in primary school.
You are encouraged to solve this task according to the task description, using any language you may know.
Only print the top half triangle of products.
ALGOL 68
<lang Algol68>main:(
INT max = 12; INT width = ENTIER(log(max)*2)+1; STRING empty = " "*width, sep="|", hr = "+" + (max+1)*(width*"-"+"+"); FORMAT ifmt = $g(-width)"|"$; # remove leading zeros #
printf(($gl$, hr)); print(sep + IF width<2 THEN "x" ELSE " "*(width-2)+"x " FI + sep); FOR col TO max DO printf((ifmt, col)) OD; printf(($lgl$, hr));
FOR row TO max DO [row:max]INT product; FOR col FROM row TO max DO product[col]:=row*col OD; STRING prefix=(empty+sep)*(row-1); printf(($g$, sep, ifmt, row, $g$, prefix, ifmt, product, $l$)) OD; printf(($gl$, hr))
)</lang> Output:
+---+---+---+---+---+---+---+---+---+---+---+---+---+ | x | 1| 2| 3| 4| 5| 6| 7| 8| 9| 10| 11| 12| +---+---+---+---+---+---+---+---+---+---+---+---+---+ | 1| 1| 2| 3| 4| 5| 6| 7| 8| 9| 10| 11| 12| | 2| | 4| 6| 8| 10| 12| 14| 16| 18| 20| 22| 24| | 3| | | 9| 12| 15| 18| 21| 24| 27| 30| 33| 36| | 4| | | | 16| 20| 24| 28| 32| 36| 40| 44| 48| | 5| | | | | 25| 30| 35| 40| 45| 50| 55| 60| | 6| | | | | | 36| 42| 48| 54| 60| 66| 72| | 7| | | | | | | 49| 56| 63| 70| 77| 84| | 8| | | | | | | | 64| 72| 80| 88| 96| | 9| | | | | | | | | 81| 90| 99|108| | 10| | | | | | | | | |100|110|120| | 11| | | | | | | | | | |121|132| | 12| | | | | | | | | | | |144| +---+---+---+---+---+---+---+---+---+---+---+---+---+
C
<lang c>#include <math.h>
- include <stdio.h>
int main(int argc, char *argv[]) {
int max = 12; char format[8]; char format2[8]; int dgts; int i,j;
dgts = (int)(.99+ log10(1.0*max*max)); sprintf(format," %%%dd", dgts); sprintf(format2,"%%%ds%%c", dgts);
printf(format2,"",'x');
for (i=1; i<=max; i++) printf(format,i);
printf("\n\n");
for (j=1; j<=max; j++) {
printf(format,j);
for(i=1; i<j; i++) printf(format2,"",' ');
for(i=j; i<=max; i++) printf(format, i*j);
printf("\n");
}
printf("\n");
return 0;
}</lang> Output:
x 1 2 3 4 5 6 7 8 9 10 11 12 1 1 2 3 4 5 6 7 8 9 10 11 12 2 4 6 8 10 12 14 16 18 20 22 24 3 9 12 15 18 21 24 27 30 33 36 4 16 20 24 28 32 36 40 44 48 5 25 30 35 40 45 50 55 60 6 36 42 48 54 60 66 72 7 49 56 63 70 77 84 8 64 72 80 88 96 9 81 90 99 108 10 100 110 120 11 121 132 12 144
C++
This is a slightly more-generalized version that takes any minimum and maximum table value, and formats the table columns.
<lang cpp>#include <iostream>
- include <iomanip>
- include <cmath> // for log10()
- include <algorithm> // for max()
size_t get_table_column_width(const int min, const int max) {
unsigned int abs_max = std::max(max*max, min*min);
// abs_max is the largest absolute value we might see. // If we take the log10 and add one, we get the string width // of the largest possible absolute value. // Add one for a little whitespace guarantee. size_t colwidth = 1 + std::log10(abs_max) + 1;
// If only one of them is less than 0, then some will // be negative. bool has_negative_result = (min < 0) && (max > 0);
// If some values may be negative, then we need to add some space
// for a sign indicator (-)
if(has_negative_result)
colwidth++;
return colwidth;
}
void print_table_header(const int min, const int max) {
size_t colwidth = get_table_column_width(min, max);
// table corner
std::cout << std::setw(colwidth) << " ";
for(int col = min; col <= max; ++col)
{
std::cout << std::setw(colwidth) << col;
}
// End header with a newline and blank line. std::cout << std::endl << std::endl;
}
void print_table_row(const int num, const int min, const int max) {
size_t colwidth = get_table_column_width(min, max);
// Header column std::cout << std::setw(colwidth) << num;
// Spacing to ensure only the top half is printed
for(int multiplicand = min; multiplicand < num; ++multiplicand)
{
std::cout << std::setw(colwidth) << " ";
}
// Remaining multiplicands for the row.
for(int multiplicand = num; multiplicand <= max; ++multiplicand)
{
std::cout << std::setw(colwidth) << num * multiplicand;
}
// End row with a newline and blank line. std::cout << std::endl << std::endl;
}
void print_table(const int min, const int max) {
// Header row print_table_header(min, max);
// Table body
for(int row = min; row <= max; ++row)
{
print_table_row(row, min, max);
}
}
int main() {
print_table(1, 12); return 0;
} </lang>
Output:
1 2 3 4 5 6 7 8 9 10 11 12 1 1 2 3 4 5 6 7 8 9 10 11 12 2 4 6 8 10 12 14 16 18 20 22 24 3 9 12 15 18 21 24 27 30 33 36 4 16 20 24 28 32 36 40 44 48 5 25 30 35 40 45 50 55 60 6 36 42 48 54 60 66 72 7 49 56 63 70 77 84 8 64 72 80 88 96 9 81 90 99 108 10 100 110 120 11 121 132 12 144
Haskell
<lang haskell>import Control.Monad import Text.Printf
main = do
putStrLn $ " x" ++ concatMap fmt [1..12]
zipWithM_ f [1..12] $ iterate (" " ++) ""
where f n s = putStrLn $ fmt n ++ s ++ concatMap (fmt . (*n)) [n..12]
fmt n = printf "%4d" (n :: Int)</lang>
Perl
<lang perl>our $max = 12; our $width = length($max**2) + 1;
printf "%${width}s", $_ foreach 'x|', 1..$max; print "\n", '-' x ($width - 1), '+', '-' x ($max*$width), "\n"; foreach my $i (1..$max) { printf "%${width}s", $_
foreach "$i|", map { $_ >= $i and $_*$i } 1..$max;
print "\n"; }</lang>
Output:
x| 1 2 3 4 5 6 7 8 9 10 11 12 ---+------------------------------------------------ 1| 1 2 3 4 5 6 7 8 9 10 11 12 2| 4 6 8 10 12 14 16 18 20 22 24 3| 9 12 15 18 21 24 27 30 33 36 4| 16 20 24 28 32 36 40 44 48 5| 25 30 35 40 45 50 55 60 6| 36 42 48 54 60 66 72 7| 49 56 63 70 77 84 8| 64 72 80 88 96 9| 81 90 99 108 10| 100 110 120 11| 121 132 12| 144
Python
<lang python>>>> size = 12 >>> for row in range(-1,size+1): if row==0: print("─"*3 + "┼"+"─"*(4*size-1)) else: print("".join("%3s%1s" % (("x","│") if row==-1 and col==0 else (row,"│") if row>0 and col==0 else (col,"") if row==-1 else ("","") if row>col else (row*col,"")) for col in range(size+1)))
x│ 1 2 3 4 5 6 7 8 9 10 11 12
───┼───────────────────────────────────────────────
1│ 1 2 3 4 5 6 7 8 9 10 11 12 2│ 4 6 8 10 12 14 16 18 20 22 24 3│ 9 12 15 18 21 24 27 30 33 36 4│ 16 20 24 28 32 36 40 44 48 5│ 25 30 35 40 45 50 55 60 6│ 36 42 48 54 60 66 72 7│ 49 56 63 70 77 84 8│ 64 72 80 88 96 9│ 81 90 99 108 10│ 100 110 120 11│ 121 132 12│ 144
>>> </lang>
The above works with Python 3.X, which uses Unicode strings by default.
Declaring a file type of UTF-8 and adding a u to all string literals to transform them into Unicode literals would make the above work in Python 2.X.
(As would using ASCII minus, plus, and pipe characters: "-", "+", "|"; instead of the non-ASCII chars used to draw a frame).
The code works fine for all values of integer 0 <= size <= 31 as above that, table numbers can get greater than the three digits allotted to them in the output formatting. This is a reasonable limitation for this format of multiplication table as other considerations, such as the width of the printed line are also excessive for large values of size.
Ruby
<lang ruby>def multiplication_table(n)
puts " " + ((" %3d" * n) % (1..n).to_a)
1.upto(n) do |x|
print "%3d " % x
1.upto(x-1) {|y| print " "}
x.upto(n) {|y| print " %3d" % (x*y)}
puts ""
end
end
multiplication_table 12</lang>
Tcl
<lang tcl>puts " x\u2502 1 2 3 4 5 6 7 8 9 10 11 12" puts \u0020\u2500\u2500\u253c[string repeat \u2500 48] for {set i 1} {$i <= 12} {incr i} {
puts -nonewline [format "%3d" $i]\u2502[string repeat " " [expr {$i*4-4}]]
for {set j 1} {$j <= 12} {incr j} {
if {$j >= $i} { puts -nonewline [format "%4d" [expr {$i*$j}]] }
} puts ""
}</lang> Output:
x│ 1 2 3 4 5 6 7 8 9 10 11 12 ──┼──────────────────────────────────────────────── 1│ 1 2 3 4 5 6 7 8 9 10 11 12 2│ 4 6 8 10 12 14 16 18 20 22 24 3│ 9 12 15 18 21 24 27 30 33 36 4│ 16 20 24 28 32 36 40 44 48 5│ 25 30 35 40 45 50 55 60 6│ 36 42 48 54 60 66 72 7│ 49 56 63 70 77 84 8│ 64 72 80 88 96 9│ 81 90 99 108 10│ 100 110 120 11│ 121 132 12│ 144