24. Score of Parentheses.cpp

/*
Score of Parentheses
====================

Given a balanced parentheses string S, compute the score of the string 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: "()"
Output: 1

Example 2:
Input: "(())"
Output: 2

Example 3:
Input: "()()"
Output: 2

Example 4:
Input: "(()(()))"
Output: 6

Note:
S is a balanced parentheses string, containing only ( and ).
2 <= S.length <= 50
*/

class Solution {
public:
    int scoreOfParentheses(string S) {
      int ans = 0,count = 0, can_add = 0;
      
      for(int i=0; i<S.size(); ++i){
        if(S[i] == '(') count++,can_add = 1;
        else {
          count--;
          if(can_add) ans += pow(2,count),can_add = 0;
        }
      }
      
      return ans;
    }
};