sorry for necro-replying

Can you comment on my solution, which benchmarks around 4 times faster than either yours or OP's solution? I tried to avoid iterating over anything more than once, and to avoid allocations where possible

The repeated access to string is cache friendly, so has a good chance to be stupid fast.
On the other hand, memory allocations are stripped to (what seems to be) a minimum.
The clever avoidance of count and no intermediate collection to store the counting is appealing to the audiance. :-)
Also, codewars community tend to favor 'less code' approach. :-))
That's my understanding, but would like to hear someone more experienced in Rust.

Fascinating work!
I wrote like 80,90 lines of code to get this passed while this guy used only few lines.
I wish I can code like you one day

why is this so highly voted? it's iterating over every string 26 times, once for every character in the alphabet. can someone explain?

smart

's' => acc *= acc
......

purely math again