Day 14: too slow. And no regexes :-(

[aoc2021.git] / 27.pl

diff --git a/27.pl b/27.pl
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+++ b/27.pl
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+#!/usr/bin/perl -w
+
+use v5.16;
+
+chomp (my $tmpl = <>);
+scalar <>;
+
+my %r;
+while (<>) {
+       chomp;
+       my ($s1, $s2, $d) = /([A-Z])/g;
+       $r{"$s1$s2"} = "$s1$d$s2";
+}
+
+for (1 .. 10) {
+       my $i = 0;
+       while ($i < length $tmpl) {
+               my $s = substr($tmpl, $i, 2);
+               if ($r{$s}) {
+                       substr($tmpl, $i, 2) = $r{$s};
+                       $i+=2;
+                       next;
+               }
+               $i++;
+       }
+}
+
+my %count;
+for ('A' .. 'Z') {
+       $count{$_} = () = $tmpl =~ /$_/g;
+}
+
+my @count = sort { $a <=> $b } grep { $_ > 0 } values %count;
+
+say $count[-1] - $count[0];
+