921-Minimum-Add-to-Make-Parentheses-Valid.cpp

class Solution {
public:
    int minAddToMakeValid(string s) {
        int open = 0;
        int close = 0;
         
        for(char c : s) {
            if(c == '(') {
                close++;
            } 
            else if(c == ')') {
                if(close > 0) {
                    close--; 
                } 
                else {
                    open++;
                }
            }
        }
        
        return open + close;
    }
};