1323-Maximum-69-Number.cpp

class Solution {
public:
    int maximum69Number (int num) {
        string ans = to_string(num);
        for(int i = 0; i < ans.size();i++){
            if(ans[i] == '6'){
                ans[i] = '9';
                break;
            }
        }
        return stoi(ans);
    }
};