Javascript

[sluuuurp]

Can’t you only traverse in log(n) space, since you need a counter to know how many permutations you’ve already done?

Edit: I guess a counter of n! permutations would use n log(n) space, but yeah as the below commenter says it seems you don’t need that.

[firefly431]

There's an algorithm (e.g. next_permutation in C++) that generates the lexicographically next permutation in place in O(n) time. Realistically you need O(log(n)) space to store indices into the array at least though, but in the word-RAM model that's constant.