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Reverse and Add given number repeatedly to get a Palindrome number

  • Difficulty Level : Basic
  • Last Updated : 07 Mar, 2022

Write a program that takes number and gives the resulting palindrome (if one exists). If it took more than 1, 000 iterations (additions) or yield a palindrome that is greater than 4, 294, 967, 295, assume that no palindrome exist for the given number.

Examples: 

Input: N = 195
Output: 9339

Input: N = 265
Output: 45254

Input: N = 196
Output: No palindrome exist

Approach: Create a reverse and add function to start with a number, reverses its digits, and adds the reverse to the original. If the sum is not a palindrome, repeat this procedure until it does.

C++




// C++ Program to implement reverse and add function
#include <bits/stdc++.h>
using namespace std;
  
/* Iterative function to reverse digits of num*/
long long reversDigits(long long num)
{
    long long rev_num = 0;
    while (num > 0) {
        rev_num = rev_num * 10 + num % 10;
        num = num / 10;
    }
    return rev_num;
}
  
/* Function to check whether the 
number is palindrome or not */
bool isPalindrome(long long num)
{
    return (reversDigits(num) == num);
}
  
/* Reverse and Add Function */
void ReverseandAdd(long long num)
{
    long long rev_num = 0;
    while (num <= 4294967295) {
        // Reversing the digits of the number
        rev_num = reversDigits(num);
  
        // Adding the reversed number
        // with the original
        num
            = num + rev_num;
  
        // Checking whether the number
        // is palindrome or not
        if (isPalindrome(num)) {
            printf("%lld\n", num);
            break;
        }
        else if (num > 4294967295) {
            printf("No palindrome exist");
        }
    }
}
  
// Driver Program
int main()
{
    ReverseandAdd(195);
    ReverseandAdd(265);
    return 0;
}

Java




// Java Program to implement reverse and add function
public class ReverseAdd {
    /* Iterative function to reverse digits of num*/
    long reversDigits(long num)
    {
        long rev_num = 0;
        while (num > 0) {
            rev_num = rev_num * 10 + num % 10;
            num = num / 10;
        }
        return rev_num;
    }
  
    /* Function to check whether he number is
           palindrome or not */
    boolean isPalindrome(long num)
    {
        return (reversDigits(num) == num);
    }
  
    /* Reverse and Add Function */
    void ReverseandAdd(long num)
    {
        long rev_num = 0;
        while (num <= 4294967295l) {
            // Reversing the digits of the number
            rev_num = reversDigits(num);
  
            // Adding the reversed number
            // with the original
            num
                = num + rev_num;
  
            // Checking whether the number
            // is palindrome or not
            if (isPalindrome(num)) {
                System.out.println(num);
                break;
            }
            else if (num > 4294967295l) {
                System.out.println("No palindrome exist");
            }
        }
    }
  
    // Main method
    public static void main(String[] args)
    {
        ReverseAdd ob = new ReverseAdd();
        ob.ReverseandAdd(195l);
        ob.ReverseandAdd(265l);
    }
}

Python3




# Python Program to implement reverse and add function
  
# Iterative function to reverse digits of num
def reversDigits(num):
    rev_num = 0
    while (num > 0):
        rev_num = rev_num * 10 + num % 10
        num = num//10
    return rev_num
  
# Function to check whether 
# the number is palindrome or not
def isPalindrome(num):
    return (reversDigits(num) == num)
  
# Reverse and Add Function
def ReverseandAdd(num):
    rev_num = 0
    while (num <= 4294967295):
        # Reversing the digits of the number
        rev_num = reversDigits(num)
  
        # Adding the reversed number 
        # with the original
        num = num + rev_num
  
        # Checking whether the number 
        # is palindrome or not
        if(isPalindrome(num)):
            print (num)
            break
        else:
            if (num > 4294967295):
                print ("No palindrome exist")
  
# Driver Code
ReverseandAdd(195)
ReverseandAdd(265)

C#




// C# Program to implement reverse and add function
using System;
  
class GFG {
    /* Iterative function to reverse digits of num*/
    static long reversDigits(long num)
    {
        long rev_num = 0;
        while (num > 0) {
            rev_num = rev_num * 10 + num % 10;
            num = num / 10;
        }
        return rev_num;
    }
  
    /* Function to check whether he number is
        palindrome or not */
    static bool isPalindrome(long num)
    {
        return (reversDigits(num) == num);
    }
  
    /* Reverse and Add Function */
    static void ReverseandAdd(long num)
    {
        long rev_num = 0;
        while (num <= 4294967295) {
            // Reversing the digits of the number
            rev_num = reversDigits(num);
  
            // Adding the reversed number
            // with the original
            num = num + rev_num;
  
            // Checking whether the number
            // is palindrome or not
            if (isPalindrome(num)) {
                Console.WriteLine(num);
                break;
            }
            else if (num > 4294967295) {
                Console.WriteLine("No palindrome exist");
            }
        }
    }
  
    // Driver code
    public static void Main()
    {
        ReverseandAdd(195);
        ReverseandAdd(265);
    }
}
  
// This code is contributed by chandan_jnu

PHP




<?php
// PHP Program to implement reverse and add function
  
/* Iterative function to reverse digits of num*/
function reversDigits($num)
{
    $rev_num = 0;
    while ($num > 0)
    {
        $rev_num = $rev_num * 10 + $num % 10;
        $num = (int)($num / 10);
    }
    return $rev_num;
}
  
/* Function to check whether he number
   is palindrome or not */
function isPalindrome($num)
{
    return (reversDigits($num) == $num);
}
  
/* Reverse and Add Function */
function ReverseandAdd($num)
{
     $rev_num = 0;
    while ($num <= 4294967295)
    {
        // Reversing the digits of the number
        $rev_num = reversDigits($num);
  
        // Adding the reversed number with
        // the original
        $num = $num + $rev_num;
  
        // Checking whether the number is
        // palindrome or not
        if (isPalindrome($num))
        {
            print($num . "\n");
            break;
        }
        else if ($num > 4294967295)
        {
            print("No palindrome exist");
        }
    }
}
  
// Driver Code
ReverseandAdd(195);
ReverseandAdd(265);
  
// This code is contributed by chandan_jnu
?>

Javascript




<script>
  
// Javascript program to implement
// reverse and add function
  
// Iterative function to reverse digits of num
function reversDigits(num)
{
    let rev_num = 0;
    while (num > 0)
    {
        rev_num = rev_num * 10 + num % 10;
        num = parseInt(num / 10, 10);
    }
    return rev_num;
}
  
// Function to check whether he number 
// is palindrome or not 
function isPalindrome(num)
{
    return(reversDigits(num) == num);
}
  
// Reverse and Add Function 
function ReverseandAdd(num)
{
    let rev_num = 0;
      
    while (num <= 4294967295)
    {
          
        // Reversing the digits of the number
        rev_num = reversDigits(num);
  
        // Adding the reversed number 
        // with the original
        num = num + rev_num;
  
        // Checking whether the number 
        // is palindrome or not
        if (isPalindrome(num))
        {
            document.write(num + "</br>");
            break;
        }
        else if (num > 4294967295)
        {
            document.write("No palindrome exist"
                           "</br>");
        }
    }
}
  
// Driver code
ReverseandAdd(195);
ReverseandAdd(265);
  
// This code is contributed by rameshtravel07  
  
</script>
Output:
9339
45254

References: https://app.assembla.com/spaces/AASU_Fall2008_ProgrammingTeam/wiki

This article is contributed by Rahul Agrawal. If you like GeeksforGeeks and would like to contribute, you can also write an article using write.geeksforgeeks.org or mail your article to review-team@geeksforgeeks.org. See your article appearing on the GeeksforGeeks main page and help other Geeks.
Please write comments if you find anything incorrect, or you want to share more information about the topic discussed above.
 


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