Day 10: quite ugly solution, does not work on examples of part 2

[aoc.git] / 2023 / 19.pl

diff --git a/2023/19.pl b/2023/19.pl
new file mode 100755 (executable)
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--- /dev/null
+++ b/2023/19.pl
@@ -0,0 +1,72 @@
+#!/usr/bin/perl -w
+
+use v5.38;
+use experimental 'multidimensional', 'for_list', 'builtin';
+use builtin 'indexed';
+use List::Util;
+use Y::AoC::Task;
+$; = ';';
+# t;
+
+my @map = map { chomp; [ split //, ".$_." ] } <>;
+push @map, [ ('.') x @map ];
+unshift @map, [ ('.') x @map ];
+my $xmax = $#{$map[0]};
+my $ymax = $#map;
+
+my ($sx, $sy);
+for my $x (0 .. $xmax) {
+for my $y (0 .. $ymax) {
+       next if $map[$y][$x] ne 'S';
+       $sx = $x; $sy = $y;
+} }
+
+say "starting at $sx, $sy";
+
+my %dirs = (
+       '|' => [ 0, -1,  0,  1],
+       '-' => [-1,  0,  1,  0],
+       'J' => [-1,  0,  0, -1],
+       'L' => [ 1,  0,  0, -1],
+       'F' => [ 1,  0,  0,  1],
+       '7' => [-1,  0,  0,  1],
+);
+
+if ($map[$sy][$sx-1] eq '-' && $map[$sy][$sx+1] eq '-') {
+       $map[$sy][$sx] = '-';
+} elsif ($map[$sy+1][$sx] eq '|' && $map[$sy-1][$sx] eq '|') {
+       $map[$sy][$sx] = '|';
+} elsif ($map[$sy][$sx-1] eq '-' && $map[$sy-1][$sx] eq '|') {
+       $map[$sy][$sx] = 'J';
+} elsif ($map[$sy][$sx-1] eq '-' && $map[$sy+1][$sx] eq '|') {
+       $map[$sy][$sx] = '7';
+} elsif ($map[$sy][$sx+1] eq '-' && $map[$sy-1][$sx] eq '|') {
+       $map[$sy][$sx] = 'L';
+} elsif ($map[$sy][$sx+1] eq '-' && $map[$sy+1][$sx] eq '|') {
+       $map[$sy][$sx] = 'F';
+}
+
+my %seen;
+my $len = 0;
+my ($px, $py);
+while (!$seen{$sx,$sy}++) {
+       my @d = $dirs{ $map[$sy][$sx] }->@*;
+       say "map: $map[$sy][$sx] @d";
+       if (!defined($px) || ($px != $d[0] || $py != $d[1])) {
+               say "first";
+               $sx += $d[0];
+               $sy += $d[1];
+               $px = -$d[0];
+               $py = -$d[1];
+       } else {
+               say "second";
+               $sx += $d[2];
+               $sy += $d[3];
+               $px = -$d[2];
+               $py = -$d[3];
+       }
+       ++$len;
+       say "at $sx $sy $map[$sy][$sx] from $px $py len $len";
+}
+
+say $len/2;