Palindrome Number

Example 1:

Input: x = 121

Output: true

Explanation: 121 reads as 121 from left to right and from right to left.

Example 2:

Input: x = -121

Output: false

Explanation: From left to right, it reads -121. From right to left, it becomes 121-. Therefore it is not a palindrome.

Example 3:

Input: x = 10

Output: false

Explanation: Reads 01 from right to left. Therefore it is not a palindrome.

public class Solution {
    public boolean isPalindrome(int x) {
        // Convert integer to string
        String s = Integer.toString(x);
        
        // Use two pointers to check if the string is a palindrome
        int left = 0, right = s.length() - 1;
        while (left < right) {
            // If characters at current positions don't match, it's not a palindrome
            if (s.charAt(left) != s.charAt(right)) {
                return false;
            }
            // Move the pointers towards the center
            left++;
            right--;
        }
        // If the loop completes without returning false, the number is a palindrome
        return true;
    }

    public static void main(String[] args) {
        Solution solution = new Solution();
        int x = -121;
        boolean result = solution.isPalindrome(x);
        System.out.println("Output: " + result);
    }
}

Explanation:-

1. isPalindrome Method:

• This method takes an integer x as input and returns a boolean value indicating whether x is a palindrome or not.
• It first converts the integer x to a string s using the Integer.toString(x) method. This allows us to easily work with individual digits of the number.
• It initializes two pointers, left and right, to traverse the string s. left starts from the beginning (index 0) of the string, and right starts from the end (index s.length() - 1) of the string.

1. Looping through the String:

• The method enters a while loop that continues as long as left is less than right. This loop compares characters from both ends of the string towards the center.
• At each iteration, it checks if the character at position left in the string is equal to the character at position right. If they are not equal, it means the number is not a palindrome, so it returns false.
• If the characters are equal, the pointers are moved towards the center by incrementing left and decrementing right.

1. Returning the Result:

• If the loop completes without returning false, it means all characters from both ends matched, indicating that the number is a palindrome. In this case, it returns true.

1. Main Method:

• The main method is where the program execution starts.
• An instance of the Solution class is created.
• An integer x with a value of -121 is declared.
• The isPalindrome method is called with x as an argument, and the result is stored in the result variable.
• Finally, the result is printed to the console.

This code effectively checks whether the given integer is a palindrome by converting it to a string and comparing characters from both ends towards the center.