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.
Method
Use stack.
Solution
class Solution(object):
def isValid(self, s):
"""
:type s: str
:rtype: bool
"""
res = []
for i in s:
if i == "[" or i == "{" or i == "(":
res.append(i)
elif i == "]" :
if res == [] or res.pop() != "[": return False
elif i =="}":
if res == [] or res.pop() != "{": return False
elif i ==")":
if res == [] or res.pop() != "(": return False
if res == []: return True
else: return False
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