adventofcode/2017/19/1.pl

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2017-12-19 16:49:15 +00:00
use 5.20.0;
use List::AllUtils qw/ first_index min max /;
use experimental qw/ postderef smartmatch /;
my @grid = map { chomp; [ ' ', split '' ] } <>;
my @c = ( 0, first_index { $_ eq '|' } $grid[0]->@* );
my @d = (1,0);
use DDP;
p @c;
my $steps;
my $safe = @grid * $grid[0]->@*;
while() {
die unless $safe--;
given( $grid[$c[0]][$c[1]] ) {
print $1 when /([A-Z])/;
when( '+' ) {
@d = next_direction();
}
}
$steps++;
last if $grid[$c[0]][$c[1]] eq 'T';
$grid[$c[0]][$c[1]] = ' ';
@c = map { $c[$_] + $d[$_] } 0..1;
last if min(@c) < 0;
last if max(@c) >= $grid[0]->@*;
# print_around();
# print @$_ for @grid;
# my $x = <STDIN>;
}
say $steps;
sub print_around {
for my $r ( max(0,$c[0]-5)..$c[0]+5 ) {
say join '', $grid[$r]->@[ max(0,$c[1]-5)..$c[1]+5 ]
}
my $x = <STDIN>;
}
sub next_direction() {
for( [0,1], [0,-1] ) {
return @$_ if $grid[$c[0]+$_->[0]][$c[1] + $_->[1]] eq '-';
}
for( [1,0], [-1,0] ) {
return @$_ if $grid[$c[0]+$_->[0]][$c[1] + $_->[1]] eq '|';
}
die join ":", @c;
}