35 lines
733 B
Perl
35 lines
733 B
Perl
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use 5.20.0;
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my $state = 'A';
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use experimental qw/ smartmatch /;
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use List::AllUtils qw/ sum /;
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my $iteration;
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my @ribbon;
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my $ri = 0;
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my %chain = (
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A => [ [ 1, 1, 'B' ], [ 0, -1, 'C' ] ],
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B => [ [ 1, -1, 'A' ], [ 1, 1, 'D' ] ],
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C => [ [ 0, -1, 'B' ], [ 0, -1, 'E' ] ],
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D => [ [ 1, 1, 'A' ], [ 0, 1, 'B' ] ],
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E => [ [ 1, -1, 'F' ], [ 1, -1, 'C' ] ],
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F => [ [ 1, 1, 'D' ], [ 1, 1, 'A' ] ],
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);
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while( $iteration++ <= 1_2481_997 ) {
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say $iteration unless $iteration % 100_000;
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my $change = $chain{$state}[ $ribbon[$ri] ];
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$ribbon[$ri] = $change->[0];
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$ri += $change->[1];
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if( $ri == -1 ) {
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unshift @ribbon, 0;
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$ri = 0;
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}
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$state = $change->[2];
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}
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say sum @ribbon;
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