20. Valid Parentheses

20. Valid Parentheses

Leetcode link for this question

Discription:

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.

Analyze:

Code 1 :

class Solution(object):
def isValid(self, s):
"""
:type s: str
:rtype: bool
"""
li=[]
left=['(','{','[']
for i in s:
if i in left:
li.append(i)
elif not li:
return False
elif i ==')' :
if li[-1]!='(':
return False
else:
li.pop()
elif i =='}' :
if li[-1]!='{':
return False
else:
li.pop()
elif  i ==']' :
if li[-1]!='[':
return False
else:
li.pop()
if li:
return False
else:
return True

Submission Result:

Status: Accepted

Runtime: 44 ms

Ranking: beats 72.46%