2109. Adding Spaces to a String

class Solution {
public:
    string addSpaces(string s, vector<int>& spaces) {
         int m = s.length();
        int n = spaces.size();

        string result = "";

        int j = 0; //to traverse in spaces vector
        for(int i = 0; i < m; i++) {
            if(j < n && i == spaces[j]) {
                result += " ";
                j++;
            }

            result += s[i];
        }

        return result;
    }
};