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
class Solution(object):
def isValid(self, s):
"""
:type s: str
:rtype: bool
"""
sta = []
for per_s in s:
if per_s=='(' or per_s=='[' or per_s=='{':
sta.append(per_s)
elif per_s==')' or per_s==']' or per_s=='}':
if sta == []: return False
temp_s = sta.pop()
if per_s==')' and temp_s=='(' or per_s==']' and temp_s=='[' or per_s=='}' and temp_s=='{':
continue
else:
return False
else:
return False
return sta == []