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Program to find all Factors of a Number using recursion
  • Last Updated : 06 Apr, 2021

Given a number N, the task is to print all the factors of N using recursion.
Examples: 
 

Input: N = 16 
Output: 1 2 4 8 16 
Explanation: 
1, 2, 4, 8, 16 are the factors of 16. A factor is a number which divides the number completely. 
Input: N = 8 
Output: 1 2 4 8 
 

 

Approach: The idea is to create a function that takes 2 arguments. The function is recursively called from 1 to N and in every call, if the number is a factor of N, then it is printed. The recursion will stop when the number exceeds N. 
Below is the implementation of the above approach:
 

C++




// C++ program to find all the factors
// of a number using recursion
 
#include <bits/stdc++.h>
using namespace std;
 
// Recursive function to
// print factors of a number
void factors(int n, int i)
{
    // Checking if the number is less than N
    if (i <= n) {
        if (n % i == 0) {
            cout << i << " ";
        }
 
        // Calling the function recursively
        // for the next number
        factors(n, i + 1);
    }
}
 
// Driver code
int main()
{
    int N = 16;
    factors(N, 1);
}

Java




// Java program to find all the factors
// of a number using recursion
 
class GFG {
 
    // Recursive function to
    // print factors of a number
    static void factors(int n, int i)
    {
 
        // Checking if the number is less than N
        if (i <= n) {
            if (n % i == 0) {
                System.out.print(i + " ");
            }
 
            // Calling the function recursively
            // for the next number
            factors(n, i + 1);
        }
    }
    // Driver code
    public static void main(String args[])
    {
        int N = 16;
        factors(N, 1);
    }
}

Python3




# Python3 program to find all the factors
# of a number using recursion
 
# Recursive function to
# prfactors of a number
def factors(n, i):
 
    # Checking if the number is less than N
    if (i <= n):
        if (n % i == 0):
            print(i, end = " ");
         
        # Calling the function recursively
        # for the next number
        factors(n, i + 1);
     
# Driver code
if __name__ == '__main__':
    N = 16;
    factors(N, 1);
 
# This code is contributed by Rajput-Ji

C#




// C# program to find all the factors
// of a number using recursion
 
using System;
 
class GFG {
 
    // Recursive function to
    // print factors of a number
    static void factors(int n, int i)
    {
 
        // Checking if the number is less than N
        if (i <= n) {
            if (n % i == 0) {
                Console.WriteLine(i + " ");
            }
 
            // Calling the function recursively
            // for the next number
            factors(n, i + 1);
        }
    }
 
    // Driver code
    public static void Main()
    {
        int n = 16;
        factors(n, 1);
    }
}

Javascript




<script>
 
// Javascript program to find all the factors
// of a number using recursion
 
// Recursive function to
// print factors of a number
function factors(n, i)
{
    // Checking if the number is less than N
    if (i <= n) {
        if (n % i == 0) {
            document.write(i + " ");
        }
 
        // Calling the function recursively
        // for the next number
        factors(n, i + 1);
    }
}
 
// Driver code
var N = 16;
factors(N, 1);
 
</script>
Output: 
1 2 4 8 16

 

Time Complexity: O(N)
 

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