Alternating Characters

Problem

https://www.hackerrank.com/challenges/alternating-characters/problem
Difficulty: Easy

Solution

Iterative

Method: Iteratively eliminate adjasent duplicates inplace
Language: C++
Time complexity: O((Length of Array)²)
Space complexity: Constant
Test result: 14/14

// Fingerprint function
int alternatingCharacters(string s) {
    int n = s.length();
    int n_init = n;
    int i = n-1;
    while(true){
        if(s[i] == s[i-1]){
            s.erase(i, 1);
            n--;
        } else {
            i--;
        }
        if(i == 0) break;
    }
    return n_init - n;
}