Raku
sub MAIN($input) {
grammar Muls {
token TOP { .*? <mul>+%.*? .* }
token mul { "mul(" <number> "," <number> ")" }
token number { \d+ }
}
my $parsedMuls = Muls.parsefile($input);
my @muls = $parsedMuls<mul>.map({.<number>».Int});
my $part-one-solution = @muls.map({[*] $_.List}).sum;
say "part 1: $part-one-solution";
grammar EnabledMuls {
token TOP { .*? [<.disabled> || <mul>]+%.*? .* }
token mul { "mul(" <number> "," <number> ")" }
token number { \d+ }
token disabled { "don't()" .*? ["do()" || $] }
}
my $parsedEnabledMuls = EnabledMuls.parsefile($input);
my @enabledMuls = $parsedEnabledMuls<mul>.map({.<number>».Int});
my $part-two-solution = @enabledMuls.map({[*] $_.List}).sum;
say "part 2: $part-two-solution";
}
Raku
Oof, my struggle to make custom index walking paths for part 1 did not pay off for part 2.
Solution
sub MAIN($input) { my $file = (open $input).slurp; my @grid is List = $file.lines».comb».list; my @transposedGrid is List = [Z] @grid; my @reversedGrid is List = @grid».reverse; my @transposedReversedGrid is List = @transposedGrid».reverse; my @horizontalScanRows is List = generateScanHorizontal(@grid); my @transposedHorizontalScanRows is List = generateScanHorizontal(@transposedGrid); my @part-one-counts = []; @part-one-counts.push(count-xmas(@grid, @horizontalScanRows)); # Right @part-one-counts.push(count-xmas(@transposedGrid, @transposedHorizontalScanRows)); # Down @part-one-counts.push(count-xmas(@reversedGrid, @horizontalScanRows)); # Left @part-one-counts.push(count-xmas(@transposedReversedGrid, @transposedHorizontalScanRows)); # Up my @diagonalScanRows is List = generateScanDiagonal(@grid); my @transposedDiagonalScanRows is List = generateScanDiagonal(@transposedGrid); @part-one-counts.push(count-xmas(@grid, @diagonalScanRows)); # Down Right @part-one-counts.push(count-xmas(@grid, @diagonalScanRows».reverse)); # Up Left @part-one-counts.push(count-xmas(@reversedGrid, @diagonalScanRows)); # Down Left @part-one-counts.push(count-xmas(@reversedGrid, @diagonalScanRows».reverse)); # Up Right my $part-one-solution = @part-one-counts.sum; say "part 1: $part-one-solution"; my @part-two-counts = []; @part-two-counts.push(countGridMatches(@grid, (<M . S>,<. A .>,<M . S>))); @part-two-counts.push(countGridMatches(@grid, (<S . S>,<. A .>,<M . M>))); @part-two-counts.push(countGridMatches(@grid, (<S . M>,<. A .>,<S . M>))); @part-two-counts.push(countGridMatches(@grid, (<M . M>,<. A .>,<S . S>))); my $part-two-solution = @part-two-counts.sum; say "part 2: $part-two-solution"; } sub count-xmas(@grid, @scanRows) { my $xmas-count = 0; for @scanRows -> @scanRow { my $xmas-pos = 0; for @scanRow -> @pos { my $char = @grid[@pos[0]][@pos[1]]; if "X" eq $char { $xmas-pos = 1; }elsif <X M A S>[$xmas-pos] eq $char { if $xmas-pos == 3 { $xmas-pos = 0; $xmas-count += 1; } else { $xmas-pos += 1; } } else { $xmas-pos = 0; } } } return $xmas-count; } sub generateScanHorizontal(@grid) { # Horizontal my $rows = @grid.elems; my $cols = @grid[0].elems; my @scanRows = (); for 0..^$rows -> $row { my @scanRow = (); for 0..^$cols -> $col { @scanRow.push(($row, $col)); } @scanRows.push(@scanRow); } return @scanRows.List».List; } sub generateScanDiagonal(@grid) { # Down-right diagonal my $rows = @grid.elems; my $cols = @grid[0].elems; my @scanRows = (); for 0..^($rows + $cols - 1) -> $diag { my @scanRow = (); my $starting-row = max(-$cols + $diag + 1, 0); my $starting-col = max($rows - $diag - 1, 0); my $diag-len = min($rows - $starting-row, $cols - $starting-col); for 0..^$diag-len -> $diag-pos { @scanRow.push(($starting-row + $diag-pos, $starting-col + $diag-pos)); } @scanRows.push(@scanRow); } return @scanRows.List».List; } sub countGridMatches(@grid, @needle) { my $count = 0; for 0..(@grid.elems - @needle.elems) -> $top { TOP-LEFT: for 0..(@grid[$top].elems - @needle[0].elems) -> $left { for 0..^@needle.elems -> $row-offset { for 0..^@needle[$row-offset].elems -> $col-offset { my $needle-char = @needle[$row-offset][$col-offset]; next if $needle-char eq "."; next TOP-LEFT if $needle-char ne @grid[$top+$row-offset][$left+$col-offset]; } } $count += 1; } } return $count; }github