856. Score of Parentheses

Given a balanced parentheses string s, return the score of the string.

The score of a balanced parentheses string is based on the following rule:

• "()" has score 1.
• AB has score A + B, where A and B are balanced parentheses strings.
• (A) has score 2 * A, where A is a balanced parentheses string.

Example 1:

Input: s = "()"
Output: 1

Example 2:

Input: s = "(())"
Output: 2

Example 3:

Input: s = "()()"
Output: 2

Constraints:

• 2 <= s.length <= 50
• s consists of only '(' and ')'.
• s is a balanced parentheses string.

• class Solution {
  public:
      int scoreOfParentheses(string s) {
          stack<int> st;
          st.push(0);
          for(auto c:s){
              if(c == '(')
                  st.push(0);
              else{
                  int v = st.top();
                  st.pop();
                  st.top() += max(2 * v,1);
              }
          }
          return st.top();
      }
  };