Palindrome Number

  

Given - number n.

Return n is palindrome or not.

1.     Create a temporary variable to store the incoming number for later.

2.     Create a variable to store the reconstructed reverse of the given number and initialize it to 0.

3.     We take the idea of dividing (%) a number by 10 that gives the units digit as remainder. (Main step to remember while answering problems like this)

4.     So, we keep a condition in while loop that number must not be 0.

5.     In while loop we take a temporary variable to store the unit's digit of the given number (this will be updated at end of loop)

6.     Now use the temp var like below

    1.     reverseNumber = reverseNumber * 10 + temporaryVariable

7.     At the end of loop we divide the given number n / 10 and update it to n, i.e n = n/10. We do this until we reach 0 and exit the loop.

8.     After that we can check whether the reverseNumber == n to return boolean value.

Java Implementation

class Solution {

    public boolean isPalindrome(int x) {

        int temp = x;

        int reverseNumber = 0;

        if (x < 0) {

            return false;

        }

        while (x != 0) {

            int zeroUnitDigit = x % 10;

            reverseNumber = reverseNumber * 10 + zeroUnitDigit;

            x = x / 10;

        }

        return (reverseNumber == temp) ? true : false;

    }

}