[leetcode] Valid Parentheses @Python
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)
復制代碼
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
