Füsilier Breitlinger

Füsilier Breitlinger

1 week ago • •

Füsilier Breitlinger
1 week ago • •

Advent of Code solutions in Perl

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AoC day 6, part 1. Fairly straightforward once you realize that all that stuff about aligned columns is irrelevant and you can just treat each line as a list of space-separated tokens. Props to List::Util for including a transpose function, even if it is named zip.

use v5.36;<br>use List::Util qw(sum0 product zip);<br><br>my %fn = (<br>    '+' => \&sum0,<br>    '*' => \&product,<br>);<br><br>my @input = zip map [split], readline;<br><br>my $sum = 0;<br>for my $col (@input) {<br>    my $op = pop @$col;<br>    $sum += $fn{$op}(@$col);<br>}<br><br>say $sum;<br>

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in reply to Füsilier Breitlinger

Füsilier Breitlinger

in reply to Füsilier Breitlinger • 1 week ago • •

re: Advent of Code solutions in Perl

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AoC day 6, part 2. A completely different approach compared to part 1. I briefly considered pre-parsing the operator line to determine column boundaries, but in the end I went with a state machine kind of approach instead.

use v5.36;<br>use List::Util qw(sum0 product);<br><br>my %fn = (<br>    '+' => \&sum0,<br>    '*' => \&product,<br>);<br><br>my $grid = do { local $/; readline };<br>my $w = index($grid, "\n") + 1;<br>my $h = $grid =~ tr/\n//;<br><br>my $sum = 0;<br><br>my ($op, @vals);<br>for my $i (0 .. $w - 1) {<br>    $op //= substr $grid, ($h - 1) * $w + $i, 1;<br>    my $val = '';<br>    for my $j (0 .. $h - 2) {<br>        my $c = substr $grid, $j * $w + $i, 1;<br>        $val .= $c<br>            if $c =~ /^\d\z/a;<br>    }<br>    if (length $val) {<br>        push @vals, $val;<br>        next;<br>    }<br>    $sum += $fn{$op}(splice @vals);<br>    $op = undef;<br>}<br><br>say $sum;<br>

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