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.
Trick:
Data structure: stack. LIFO (Last in first out)
class Solution: # @return a boolean def isValid(self, s): stack = [] left, right = ‘([{‘, ‘)]}‘ for i in s: if i in left: stack.append(i); continue for j in range(3): if right[j] == i: if not stack or stack[-1] != left[j]: return False else: stack.pop() continue return not stack
[leetcode] Valid Parentheses @Python
原文：http://www.cnblogs.com/asrman/p/4002832.html