leetcode-856 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:

1. S is a balanced parentheses string, containing only ( and ).

2. 2 <= S.length <= 50

想法：设立三个变量，一个变量result代表最终的运算结果，初始化为0,。一个变量left代表左括号的个数，并且初始为1。一个变量right代表有括号的个数，初始为0。如何是Example 1 和Example 3这种情况，直接统计匹配的个数即可。对于Example 2这种情况，其数学含义表示为2的次幂，此时只需统计左后括号的差值。

class Solution {
public:
    int scoreOfParentheses(string S) {
        ;
        ;
        ;
        int len = S.size();
         == len)
            return result;
         ; i <= len ; i++){
            if(S[i] == '('){
                left++;
            }else{
                right++;
                ] == '('){
                    result+=pow(,left-right);
                }
            }
        }
        return result;
    }
};