423. 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.
Example
Example 1:
Input: "([)]" Output: False
Example 2:
Input: "()[]{}"
Output: True
Challenge
Use O(n) time, n is the number of parentheses.
class Solution:
"""
@param s: A string
@return: whether the string is a valid parentheses
"""
def isValidParentheses(self, s):
# write your code here
valarr = []
for each in s:
print(valarr)
if each == '{':
valarr.append('{')
if each == '(':
valarr.append('(')
if each == '[':
valarr.append('[')
if each == '}':
if len(valarr) == 0 or valarr.pop() != '{':
return False
if each == ')':
if len(valarr) == 0 or valarr.pop() != '(':
return False
if each == ']':
if len(valarr) == 0 or valarr.pop() != '[':
return False
if len(valarr) == 0:
return True
else:
return False
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