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125.py
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46 lines (38 loc) · 1.12 KB
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'''
125. Valid Palindrome
Given a string, determine if it is a palindrome,
considering only alphanumeric characters and ignoring cases.
For example,
"A man, a plan, a canal: Panama" is a palindrome.
"race a car" is not a palindrome.
Note:
Have you consider that the string might be empty? This is a
good question to ask during an interview.
For the purpose of this problem, we define empty string as valid palindrome.
'''
class Solution(object):
def isPalindrome(self, s):
"""
:type s: str
:rtype: bool
"""
if len(s) < 2:
return True
start = 0
end = len(s) - 1
while start < end:
while not s[start].isalnum() and start < end:
start += 1
while not s[end].isalnum() and start < end:
end -= 1
# print((start, end))
# print((s[start], s[end]))
if s[start].lower() != s[end].lower():
return False
start += 1
end -= 1
return True
if __name__ == "__main__":
s = "a."
sol = Solution()
print(sol.isPalindrome(s))