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#!/usr/bin/perl
# Perl Weekly Challenge - 084
# - https://perlweeklychallenge.org/blog/perl-weekly-challenge-084/
#
# Task 2 - Find Square
#
# Author: Niels 'PerlBoy' van Dijke
use 5.16.3; # Matching the CentOS 7 distro I'm using
use strict;
use warnings;
use List::Util qw(min first sum);
use Data::Printer;
sub checkMatrix($);
sub findNumberOfSquares($);
sub printMatrix($);
my $M = [
[qw(1 1 0 1)],
[qw(1 1 0 0)],
[qw(0 1 1 1)],
[qw(1 0 1 1)],
];
printf "Input:\n%s\n", printMatrix($M);
printf "\n";
printf "Output: %d\n", findNumberOfSquares($M);
sub checkMatrix($) {
my ($ar) = @_;
my ($dx, $dy) = (scalar @{$ar->[0]}, scalar @$ar);
foreach my $row (@$ar) {
die "Matrix size issue"
unless (scalar @$row == $dx);
die "Only '0' or '1' allowed"
unless (scalar(grep { /^[01]$/ } @$row) == $dx);
}
return ($dx, $dy);
}
sub findNumberOfSquares($) {
my ($ar) = @_;
my ($dX, $dY) = checkMatrix($M);
my $nOs = 0;
for my $dim (2 .. min($dX, $dY)) {
for my $row (0 .. $dY - $dim) {
for my $col (0 .. $dX - $dim) {
my @cells = (
$ar->[$row][$col], #TL
$ar->[$row + $dim - 1][$col], #TR
$ar->[$row][$col + $dim - 1], #BL
$ar->[$row + $dim - 1][$col + $dim - 1], #BR
);
$nOs++ if (sum(@cells) == 4);
}
}
}
return $nOs;
}
sub printMatrix($) {
my ($ar) = @_;
return join("\n", map { '[ '.join(' ', @{$_}).' ]' } @$ar);
}
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