MUYANG GUO / INDEX

LeetCode

LeetCode 856 Score Of Parentheses - Medium

856. Score of Parentheses -- Medium

·1 min read·#LeetCode#Medium#Python

856. Score Of Parentheses — Medium

Open on LeetCode

Problem

  1. Score of Parentheses -- Medium

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

Solution

class Solution:
    def scoreOfParentheses(self, S: str) -> int:
        #用stack。当碰到"("压入栈， 碰到")"，
        #往前搜索第一个"("，如果中间有数字， 取出数字求和并乘以2后压入栈 
        #没有数字就直接压入"1" stack中所有的数字相加就是答案
        stack = []
        for c in S:
            if c != ')':
                stack.append(c)
            else:
                if stack[-1] == '(':
                    stack.pop()
                    stack.append(1)
                else:
                    calc = 0
                    pre = stack.pop()
                    while pre != '(':
                        calc += pre
                        pre = stack.pop()
                    stack.append(calc * 2)
        calc = 0
        while stack:
            calc += stack.pop()
        return calc

Comments