Recursion: Check if a number is palindrome using recursion

Coding Interview Questions

1 min read

Problem Statement:

Given an integer “n”, you need to check if the number is palindrome or not.

A number when reversed, will remains the same.

Example:

Input: 

n = 12321
Output: Yes

Solution Explanation:

Solution is very simple.

Call a recursive function and then reverse the number using recursion.

Then in the main function, check if the original number is same as reversed number and return the result.

Time Complexity: O(log n) number of digits that needs to reverse
Space Complexity: O(log n) for stack space

Code Solution

#include <iostream>
#include <vector>
#include <queue>
#include <stack>
using namespace std;

int revrse_num(int n, int temp)
{
    if (n == 0)
        return temp;

    temp = (temp * 10) + (n % 10);

    return revrse_num(n / 10, temp);
}

int main()
{

    int n = 12321;
    
    int temp = revrse_num(n, 0);
  
    if (temp == n)
        cout << "yes" << endl;
    else
        cout << "no" << endl;
    return 0;
}