Description

Submission

class Solution {
public:
    string minRemoveToMakeValid(string s) {
        int left = 0, right = 0;
        string tmp;

        for(char ch: s) {
            if(ch == '(') {
                ++left;
                tmp.push_back(ch);
            } else if(ch == ')') {
                if(!left) ++right;
                else {
                    --left;
                    tmp.push_back(ch);
                }
            } else {
                tmp.push_back(ch);
            }
        }

        string ret;
        for(int i = tmp.length() - 1; i >= 0; --i) {
            if(tmp[i] == '(' && left > 0) {
                --left;
            } else {
                ret.push_back(tmp[i]);
            }
        }

        reverse(ret.begin(), ret.end());
        return ret;
    }
};