Your solution being too slow is not a kata issue.

Note that inputs in this kata can be very large numbers, like count_ones(189700847246574, 320377134968482). Your current solution cannot handle numbers this big. It is even written in the description.

A hundred lines...
But performance seems to be just fine: my program counted the number of all ones from 1 to 999999999999999999 instantly.

It was a very interesting kata, I liked it.
Solved the task using permutations with repetition.

Scala translation

Nice kata, great to practice with, well done.

Unless description was changed:

... between 'left' and 'right' (including both)

Heads up. Both left and right are included in the count. I wasted nearly an hour wondering why my result was off by a tiny amount

D translation

PHP Translation. Please review and approve.

approved

Approved

approved

approved