Just for the sake of having another solution for the same problem, here's the basically-zero-thought-required brute-force search solution in C: https://gist.github.com/arirahikkala/ef1a07dbd5a8ca3a077c03c...

Not as fast as dietrichepp's solution, but not terrible either, and probably the winner in terms of memory use. Since there's no state to keep track of, adding parallelism with OpenMP was trivial, too.