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Tested Python solution for LeetCode 125 with 16 pytest cases. Generate a practice environment with lcpy.
lcpy gen -n 125 # by problem number
lcpy gen -s valid_palindrome # by problem name
s, return true if it is a palindrome, or false otherwise.
Input: s = "A man, a plan, a canal: Panama"
Output: true
Input: s = "race a car"
Output: false
Input: s = " "
Output: true
1 <= s.length <= 2 * 10^5s consists only of printable ASCII characters.class Solution:
# Time: O(n)
# Space: O(1)
def is_palindrome(self, s: str) -> bool:
left, right = 0, len(s) - 1
while left < right:
while left < right and not s[left].isalnum():
left += 1
while left < right and not s[right].isalnum():
right -= 1
if s[left].lower() != s[right].lower():
return False
left += 1
right -= 1
return True
| Time | Space |
|---|---|
| O(n) | O(1) |