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#!/usr/bin/perl
# Perl Weekly Challenge - 065
#
# Task 2 - Palindrome Partition
#
# Author: Niels 'PerlBoy' van Dijke
use strict;
use warnings;
use List::Util qw(max);
sub getPalindromes ($);
my @input = (
'aabaab',
'abbaba',
'zabcbaz',
'cedzdebaaccaa',
);
my $minlen = 2;
my $maxlen = max(map{length($_)} @input);
my %pRE;
# Building some "palindrome detection regexp'es" for later use
for my $len ($minlen .. $maxlen) {
my $half = int($len/2);
$pRE{$len} = sprintf('(.*?)((%s)%s%s)(?<right>.*)',
join(')(', ('.') x $half),
($len % 2 == 0 ? '' : '.'),
join('', map ( '\\'.($half - $_ + 3), 1 .. $half)));
}
for my $input (@input) {
my @palindromeSolutions = getPalindromes($input);
print "'$input' contains the following unique palindromes:\n";
my $solution = 1;
foreach my $p (@palindromeSolutions) {
printf "%d)\t%s\n", $solution++, join(', ', @$p);
}
}
sub getPalindromes ($) {
my ($input) = @_;
my @p;
for my $i (2 .. length($input)) {
if ($input =~ m#$pRE{$i}#) {
my ($left, $llen, $palindrome, $right) = ($1, length($1), $2, $+{right});
next if (defined $llen && $llen > 1 && $left =~ m#$pRE{$llen}#);
my @pr;
if (length($right) > 1 ) {
@pr = getPalindromes($right);
}
if (@pr) {
map { push(@p, [$palindrome, @{$_}]) } @pr;
} else {
push(@p, [$palindrome]);
}
}
}
return @p;
}
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