39 lines
530 B
Perl
39 lines
530 B
Perl
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package part2;
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use 5.20.0;
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use warnings;
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use List::AllUtils qw/ /;
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require './part1.pm';
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use experimental qw/ signatures postderef /;
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use Memoize;
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memoize('ways');
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sub ways($first, @rest) {
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return 1 unless @rest;
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my $ways = 0;
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while( my $next = shift @rest ) {
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last if $next - $first > 3;
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$ways += ways($next, @rest);
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}
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return $ways;
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}
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sub solution(@lines) {
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@lines = sort {$a<=>$b}@lines;
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unshift @lines, 0;
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push @lines, $lines[-1] + 3;
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return ways(@lines);
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}
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1;
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