1249

class Solution {
public:
    string minRemoveToMakeValid(string s) {
        int open = 0;
        string ans;
        for(char c: s){
            if(c == '(') open++, ans += c;
            if(c == ')' && open-1 >= 0) open--, ans += c;
            if(c != '(' && c != ')') ans += c;
        }
        s = ans;
        if(open){
            reverse(ans.begin(), ans.end());
            s = "";
            for(char c: ans){
                if(c == '(' && open) open--;
                else s += c;
            }
            reverse(s.begin(), s.end());
        }
        return s;
    }
};