LeetCode - 020
原题
https://leetcode.com/problems/valid-parentheses/
题干
Given a string containing just the characters '(', ')', '{', '}', '[' and ']', determine if the input string is valid.
An input string is valid if:
Open brackets must be closed by the same type of brackets. Open brackets must be closed in the correct order. Note that an empty string is also considered valid.
Example 1:
Input: "()" Output: true Example 2:
Input: "()[]{}" Output: true Example 3:
Input: "(]" Output: false Example 4:
Input: "([)]" Output: false Example 5:
Input: "{[]}" Output: true
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解
class Solution:
def isValid(self, s):
"""
:type s: str
:rtype: bool
"""
while '[]' in s or '()' in s or '{}' in s:
s = s.replace('[]','').replace('()','').replace('{}','')
return len(s) == 0解
class Solution:
def isValid(self, s):
"""
:type s: str
:rtype: bool
"""
stack = []
left = '({['
right = ']})'
for chart in s:
if chart in left:
stack.append(chart)
if chart in right:
if not stack:
return False
temp = stack.pop()
if chart == '}' and temp != '{':
return False
if chart == ']' and temp != '[':
return False
if chart == ')' and temp != '(':
return False
return stack == []本文参与 腾讯云自媒体分享计划，分享自微信公众号。
原始发表：2019-06-14，如有侵权请联系 cloudcommunity@tencent.com 删除
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