in reply to Re: Patience Sorting To Find Longest Increasing Subsequence
in thread Patience Sorting To Find Longest Increasing Subsequence
It does not currently handle exact matches since there should not be any duplicates in the list (1..N). I did leave this open as a question to ponder and it should be fairly trivial to adapt if you decide it is safe to do so ;-)sub Long_Inc_Sub { my @list = @_; my (@pile, @seq); for my $num (@list) { if (@pile) { if ($num < $pile[-1][-1][VAL]) { my ($beg, $end) = (0, $#pile); while ($beg <= $end) { my $mid = int(($beg + $end) / 2); if ($num < $pile[$mid][-1][VAL]) { $end = $mid - 1; } else { $beg = $mid + 1; } } my $prev = $beg ? $#{$pile[$beg - 1]} : undef; push @{$pile[$beg]}, [$num, $prev]; } else { push @pile, [[$num, $#{$pile[-1]}]]; } } else { push @pile, [[$num, undef]]; } } my ($prev, $len) = ($#{$pile[-1]}, scalar @pile); while ($len--) { $seq[$len] = $pile[$len][$prev][VAL]; $prev = $pile[$len][$prev][PREV]; } return @seq; }
Cheers - L~R
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