[LeetCode] Valid Palindrome

문제 링크 >> https://leetcode.com/problems/valid-palindrome/

 

 

📋 문제

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.

 

 

👉 입출력

Example 1:

Input: s = "A man, a plan, a canal: Panama"
Output: true
Explanation: "amanaplanacanalpanama" is a palindrome.

Example 2:

Input: s = "race a car"
Output: false
Explanation: "raceacar" is not a palindrome.

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.

 

 

💡 사용된 개념

✔️ str.isalnum()

문자열이 알파벳([a-zA-Z])과 숫자([0-9])로만 구성되었는지 확인하는 파이썬의 문자열 메서드이다.

문자열이 모두 알파벳과 숫자로만 구성되었다면 True, 아니면 False를 반환한다.

 

 

📝 풀이

class Solution:
    def isPalindrome(self, s: str) -> bool:
        s = ''.join(filter(str.isalnum, s)).lower()
        return True if s==s[::-1] else False

 

 

🔍 참조

str.isalnum() http://www.w3big.com/ko/python/att-string-isalnum.html