checks for negative numbers

This solution is at least 8 years old....

using var is a bad practice nowdays

let's code and play AoE. it's ok. Good luck

thanks for the explanation!

Could you explain why it has polynomial time complexity and not quadratic O(n^2)?

loll

I mean it works as you say. Plus, this is common behavior. C and C++ return the same. You'd be adding extra code to handle something that is internally handled for you.

I also thought about this problem.

One solution to deal with it is to remove repeated characters from the original string then test on the new string.

( ͡° ͜ʖ ͡°)