Multiplication tables
You are encouraged to solve this task according to the task description, using any language you may know.
Produce a formatted 12×12 multiplication table of the kind memorised by rote when in primary school.
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