www.mikescher.com/www/statics/euler/euler_062_explanation.md

Only after at least sixty-two mathematical programs in befunge you will truly appreciate a hashtable.

For real, everything would be so much better if I could retrieve this stuff in O(1).

My approach is pretty straight-forward. We calculate an permutation-insensitive hash. Then store them together with the times it appeared in a hashmap (I mean a list -.-). Now we just go through all the cubes until a single hash appeared five times. In C# with a Dictionary this takes around 10ms.