Check if given String is Palindrome or not - The Coding Shala

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Check if given String is Palindrome or not

Given a string, determine if it is a palindrome, considering only alphanumeric characters and ignoring cases.

Note: For the purpose of this problem, we define empty string as valid palindrome.

Example 1:

Input: "A man, a plan, a canal: Panama"

Output: true

Example 2:

Input: "race a car"

Output: false

Palindrome String Java Program

Method 1:

We will check char if they are alphanumeric then will compare them.

Java Code:

class Solution {
    public boolean isPalindrome(String s) {
        int i=0;
        int len = s.length()-1;
        s = s.toUpperCase();
        System.out.println(s);
        while(i<=len){
            if(!Character.isLetterOrDigit(s.charAt(i))) i++;
            else if(!Character.isLetterOrDigit(s.charAt(len))) len--;
            else{
                if(s.charAt(i) != s.charAt(len)) return false;
                i++;
                len--;
            }
        }
        return true;
    }
}

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