Number of Substring of One Type of Letter

1

This is a fairly easy problem but I’m having a problem with one of the test cases. The code is short and pretty simple, but I can’t see where can the mistake be. The code is:

#include <bits/stdc++.h>
using namespace std;

int main(){
    string str;
    getline(cin, str);
    char prev, cur;
    int add = 1, total = 1;
    for(int i = 1; i < str.length(); i++){
        prev = str.at(i-1);
        cur = str.at(i);
        if(prev == cur){
            add++;
        }
        else{
            add = 1;
        }
        total += add;
    }
    cout << total;
}

Thanks for your help!

2

What is your code supposed to be doing? What is going wrong? Where is the error occurring? What have you tried?