• raised as an issue above
• the list of installed Python packages on Codewars is here. If a package is not listed there it is not available. You can request new packages here.

It would help to even mention what things determine the selection of i and j during if X[i] > X[j] then X[i] = X[i] - X[j]. Is it merely 'whichever pair leads to the most significant influence on the smallest end result'? (Don't tell me, but on the side, I wonder: Is that mathematically equivalent to 'whichever pair makes the largest subtraction available immediately', or is it more involved, as in Pyramid Slide Down?) I looked at this a while back and it didn't make enough sense to even begin. Maybe doing that other kata in the meantime helped somewhat.

You are right. Tried with profiler on long ints (10k-5m digits) - the most time consuming operation inevitably is building the result and your way (from string) is way faster.

Just realized that int operations is not O(1) anymore when python unlimited ints is involved.