More like 4x or 8x the memory (of an ASCII string) if you just use pointers or size_t’s. Abstractly, you need at minimum (n log n) memory to represent a permut

More like 4x or 8x the memory (of an ASCII string) if you just use pointers or size_t’s. Abstractly, you need at minimum (n log n) memory to represent a permutation, which is what you’re doing.