Reverse and Add given number repeatedly to get a Palindrome number

Last Updated : 31 Oct, 2023

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 reverseDigits(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 (reverseDigits(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 = reverseDigits(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 reverseDigits(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 (reverseDigits(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 = reverseDigits(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 reverseDigits(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 (reverseDigits(num) == num)

# Reverse and Add Function
def ReverseandAdd(num):
    rev_num = 0
    while (num <= 4294967295):
        # Reversing the digits of the number
        rev_num = reverseDigits(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 reverseDigits(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 (reverseDigits(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 = reverseDigits(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
JavaScript
<script>

// Javascript program to implement
// reverse and add function

// Iterative function to reverse digits of num
function reverseDigits(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(reverseDigits(num) == num);
}

// Reverse and Add Function 
function ReverseandAdd(num)
{
    let rev_num = 0;
    
    while (num <= 4294967295)
    {
        
        // Reversing the digits of the number
        rev_num = reverseDigits(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>
PHP
<?php
// PHP Program to implement reverse and add function

/* Iterative function to reverse digits of num*/
function reverseDigits($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($num)
{
    return (reverseDigits($num) == $num);
}

/* Reverse and Add Function */
function ReverseandAdd($num)
{
     $rev_num = 0;
    while ($num <= 4294967295)
    {
        // Reversing the digits of the number
        $rev_num = reverseDigits($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
?>

Output
9339
45254

Time complexity: O(log N) for a given input

Auxiliary space: O(1) because constant variables have been used

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

This article is contributed by Rahul Agrawal.

 

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Article Tags:
Mathematical
DSA
Reverse

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