Example: Valid Palindrome - rFronteddu/general_wiki GitHub Wiki

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.

Solution

To determine if a given string is a palindrome after converting all uppercase letters to lowercase and removing all non-alphanumeric characters, you can follow these steps:

• Normalize the String: Convert all characters to lowercase and remove non-alphanumeric characters.
• Check for Palindrome: Use two pointers to compare characters from the start and end of the string, moving towards the center.

public class Solution {
    public boolean isPalindrome(String s) {
        // Convert the string to lowercase and remove non-alphanumeric characters
        s = s.toLowerCase().replaceAll("[^a-z0-9]", "");
        
        // Initialize two pointers
        int left = 0, right = s.length() - 1;
        
        // Compare characters from both ends towards the center
        while (left < right) {
            if (s.charAt(left) != s.charAt(right)) {
                return false; // Characters do not match
            }
            left++;
            right--;
        }
        
        return true; // All characters matched
    }
}