Easy

Quiz

#125 Valid Palindrome

APPROACH

A string is a palindrome if, after lowercasing all letters and removing every non-alphanumeric character, it reads the same forwards and backwards.

Given a string s, return true if it qualifies as a palindrome, or false otherwise.

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.

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