parentheses

class Solution {
public:

    int scoreOfParentheses(string S) {
        stack<char> p;
        stack<int> v;

        for (int i = 0; i < S.size(); ++i) {
            if (S[i] == '(') {
                p.push('(');
            } else {
                int total = 0;
                while (p.top() != '(') {
                    total += v.top();
                    p.pop();
                    v.pop();
                }


                if (total > 0) {
                    v.push(total * 2);
                } else {
                    v.push(1);
                }

                p.pop();
                p.push('*');
            }
        }

        int sum = 0;
        while (!v.empty()) {
            sum += v.top();
            v.pop();
        }

        return sum;
    }
};