I haven't tried to understand every line, but where exactly is the performance gain compared to the naive algorithm? Instead of comparing m positions you compare 2^(m-1) patterns? 
for my $pat (1 .. 2**$m-1) {
  ...
  for my $i (0 .. $n-2) {
    for my $j ( $i+1 .. $n-1 ) {
      ...
    }
  }
}

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In reply to Re^2: pattern finding algorithm by lima1
in thread pattern finding algorithm by kdt2006

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