What is palindrome ?
- A palindrome is a word, number, phrase, or other sequence of characters which reads the same from backward or forward direction.
- Palindromic number is a number whose digits, with decimal representation are the same read backward.
- For example:
- 121, 12321 etc. are palindromic numbers.
- We will use iterative or non recursive algorithm to check given number is palindrome.
Examples of palindromic & non-palindromic numbers:
| S. No. | Input number | Reverse(input number) | isPalindrome |
|---|---|---|---|
| 1 | 1234 | 4321 | No |
| 2 | 12321 | 12321 | Yes |
| 3 | 4554 | 4554 | Yes |
| 4 | 569 | 965 | No |
Algorithm: check given input number is palindrome
- Read input number from console.
- Reverse given input number.
- Compare given number equals reversed number.
- If reverse number is equal to given number then number is palindrome.
- else, given number is not palindrome.
Program: check given integer is palindromic number using java
package org.learn;import java.util.Scanner;public class PalindromeNumber { public static void main(String[] args) { try (Scanner scanner = new Scanner(System.in)) { System.out.printf("Enter input number : "); int inputNumber = scanner.nextInt(); int reverseNumber = reverseNumber(inputNumber); if(inputNumber == reverseNumber) { System.out.printf("Input number = %d is palindrome",inputNumber); } else { System.out.printf("Input number = %d is not a palindrome",inputNumber); } } } private static int reverseNumber(int inputNumber) { int reverseNumber = 0; int digit = 0; while (inputNumber > 0) { // get last digit e.g. 123 % 10 = 3 digit = inputNumber % 10; // after every loop get the next number // which is at 10 place from current number. reverseNumber = reverseNumber * 10 + digit; inputNumber /= 10; } return reverseNumber; }} |
Ouput: check given integer is palindrome number using java
Enter input number : 1221Input number = 1221 is palindromeEnter input number : 12345Input number = 12345 is not a palindrome |