812 B
812 B
My first attempt at this problem took over 5 hours to compute and had a complexity of O(n^3).
The problem is that you need a square root to inverse the pentagonal formula and Befunge has no square root function. So I needed to implement my own version of integer square roots in Befunge (see wikipedia). The program is still not really fast but it's good that I managed to speed it up to a time where you can execute it without waiting the whole night.
Also this program is nicely compact, by the time I'm writing this my Befunge interpreter BefunExec has gotten a display of all possible paths a program can take. And if you look at the graph of this program, it looks pretty interesting...