You learned a lot of this language with your solution. As did I with my inefficient shell-script-like solution. And now with this solution you see, that it can be much much easier. Doesn’t have to do much with the language.

lolol

I must be not suitable for learning this language

Test failed with s = "VLntuZwiiuRPgUb99999999999999999999999999999999999999999999999999999999999999999999999999999"
Expected "VLntuZwiiuRPgUb100000000000000000000000000000000000000000000000000000000000000000000000000000"
But got "VLntuZwiiuRPgUb99999999999999999999999999999999999999999999999999999999999999999999999999999" at src/lib.rs:59:9

I hate this one