sub inc(Array:D $o, Int:D \row, Int:D \col) {
$o[row;col]++ if 0 ≤ row ≤ 9 && 0 ≤ col ≤ 9 && $o[row;col] != 0;
}
sub flash(Array:D $o, UInt:D \row, UInt:D \col) {
$o[row;col] = 0;
([-1,-1], [-1,0], [-1,1],
[ 0,-1], [ 0,1],
[ 1,-1], [ 1,0], [ 1,1]
).map({ inc($o, row + .[0], col + .[1]) });
}
my $o .= push([.comb».UInt]) for $*IN.lines;
my ($round, $cnt) = (1, 0);
loop {
(^10 X ^10).map({ ++$o[.[0];.[1]] });
my $cnt1 = 0;
loop {
my $cnt0 = 0;
for ^10 X ^10 -> (\row, \col) {
if $o[row;col] > 9 {
flash($o, row, col);
++$cnt0;
}
}
$cnt1 += $cnt0;
last unless $cnt0 > 0;
}
$cnt += $cnt1;
put 'part 1: ', $cnt if $round == 100;
last if $cnt1 == 100;
++$round;
}
put 'part 2: ', $round;
