66 lines
1.3 KiB
Perl
66 lines
1.3 KiB
Perl
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package Part1;
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use Math::Vector::Real;
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use 5.36.0;
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no warnings qw/ uninitialized /;
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sub read_input ($file) {
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my @grid = map { [ split '' ] } $file->lines({chomp=>1});
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return \@grid;
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}
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my @directions = map { V(@$_) } [-1,0], [ 0,1], [1,0], [0,-1];
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sub find_guard($grid) {
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for my $i (0..$grid->$#* ) {
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for my $j ( 0..$grid->[0]->$#* ) {
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return V($i,$j) if $grid->[$i][$j] eq '^';
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}
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}
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die "didn't find the guard!";
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}
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use List::AllUtils qw/ any /;
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sub inside_grid($grid,$guard) {
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return 0 if any { $_ < 0 } @$guard;
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return $grid->[$guard->[0]][$guard->[1]];
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}
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sub solve ($grid) {
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use DDP;
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my $guard = find_guard($grid);
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my $current_direction = 0;
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use Clone qw/ clone /;
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$grid = clone($grid);
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my %seen;
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$seen{"$guard"}++;
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while() {
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my $ahead = V(@$guard) + $directions[$current_direction];
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last unless inside_grid($grid,$ahead);
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if( $grid->[$ahead->[0]][$ahead->[1]] eq '#' ) {
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$current_direction++;
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$current_direction %= @directions;
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redo;
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}
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$guard = $ahead;
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$seen{"$guard"}++;
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$grid->[$ahead->[0]][$ahead->[1]] = 'X';
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}
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use DDP;
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# p %seen;
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# p $guard;
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# for my $l ( @$grid ) {
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# say join '', @$l;
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# }
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return scalar keys %seen;
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}
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1;
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