Question
A phrase is a palindrome if, after converting all uppercase letters into lowercase letters and removing all non-alphanumeric characters, it reads the same forward and backward. Alphanumeric characters include letters and numbers.
Given a string s, return true if it is a palindrome, or false otherwise.
Example 1:
Input: s = "A man, a plan, a canal: Panama"
Output: true
Explanation: "amanaplanacanalpanama" is a palindrome.
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Example 2:
Input: s = "race a car"
Output: false
Explanation: "raceacar" is not a palindrome.
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Example 3:
Input: s = " "
Output: true
Explanation: s is an empty string "" after removing non-alphanumeric characters.
Since an empty string reads the same forward and backward, it is a palindrome.
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My Answer
class Solution:
def isPalindrome(self, s: str) -> bool:
arr = []
for ch in s:
if ch.isalnum():
arr.append(ch.lower())
if arr[::-1] == arr:
return True
else: return False
Python
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Optimized Version
No Optimization needed
Python
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arr[::-1]이 reversed array를 리턴한다는걸 알면 편해진다. reversed()함수 써도 된다
isalnum은 알파벳이나 숫자인지 판단하고, isDigit() or isalpha()로 해도 동일하다.
