[Leetcode][Python]20: Valid Parentheses
浏览数：179 /
时间：2015年06月08日
# -*- coding: utf8 -*-
‘‘‘
__author__ = ‘[email protected]‘
20: Valid Parentheses
https://oj.leetcode.com/problems/valid-parentheses/
Given a string containing just the characters ‘(‘, ‘)‘, ‘{‘, ‘}‘, ‘[‘ and ‘]‘, determine if the input string is valid.
The brackets must close in the correct order, "()" and "()[]{}" are all valid but "(]" and "([)]" are not.
===Comments by Dabay===
用一个stack来保存左括号，如果来的是对应的右括号，就pop一个；如果来的是不对应的右括号，直接return False。
‘‘‘
class Solution:
# @return a boolean
def isValid(self, s):
stack = []
for c in s:
if c in "([{":
stack.append(c)
else:
if len(stack) == 0:
return False
if (
(c == ")" and stack[-1] == "(") or
(c == "]" and stack[-1] == "[") or
(c == "}" and stack[-1] == "{")
):
stack.pop()
else:
return False
else:
return len(stack) == 0
def main():
sol = Solution()
print sol.isValid("()[]{}")
if __name__ == ‘__main__‘:
import time
start = time.clock()
main()
print "%s sec" % (time.clock() - start)
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