[vlad003]

I don't know Perl, so I rewrote it in Python in an attempt to understand what's going on: [link redacted]

I'm not storing key,value pairs for elements that don't exist (not sure what the Perl code's doing), so it shouldn't be too bad in terms of space used.

[woadwarrior01]

I'm not entirely sure about this, but it looks more like Counting sort [1], than Pigeonhole sort.

[1]: https://en.wikipedia.org/wiki/Counting_sort