Print the kth common factor of two numbers

Given three numbers x, y and k, find the k’th common factor of x and y. Print -1 if there are less than k common factors of x and y.
Examples :

Input : x = 20, y = 24
        k = 3
Output : 4
Common factors are 1, 2, 4, ...

Input : x = 4, y = 24
        k = 2
Output : 2

Input : x = 22, y = 2
        k = 3
Output : -1

We find the smaller of two numbers as common factor cannot be greater than the smaller number. Then we run a loop from 1 to the smaller number. For every number i, we check if it is a common factor. If yes, we increment count of common factors.

Below is the Implementation :

C++

filter_none

edit
close

play_arrow

link
brightness_4
code

// C++ program to find kth common factor
// of two numbers
#include<iostream>
using namespace std;
  
// Returns k'th common factor of x and y.
int findKCF(int x, int y, int k)
{
   // Find smaller of two numbers
   int small = min(x, y);
  
   // Count common factors until we either
   // reach small or count becomes k.
   int count = 1;
   for (int i=2; i<=small; i++)
   {
      if (x % i==0 && y % i == 0)
         count++;
      if (count == k)
         return i;
   }
  
   // If we reached small
   return -1;
}
  
// Driver code
int main()
{
   int x = 4, y = 24, k = 3;
   cout << findKHCF(x, y, k);
   return 0;
}

chevron_right


Java

filter_none

edit
close

play_arrow

link
brightness_4
code

// Java program to find kth 
// common factor of two numbers
import java.lang.*;
  
class GFG {
      
// Returns k'th common factor of x and y.
static int findKHCF(int x, int y, int k) {
      
    // Find smaller of two numbers
    int small = Math.min(x, y);
  
    // Count common factors until we either
    // reach small or count becomes k.
    int count = 1;
    for (int i = 2; i <= small; i++) {
    if (x % i == 0 && y % i == 0)
        count++;
    if (count == k)
        return i;
    }
  
    // If we reached small
    return -1;
}
  
// Driver code
public static void main(String[] args) {
      
    int x = 4, y = 24, k = 3;
    System.out.print(findKHCF(x, y, k));
}
}
  
// This code is contributed by Anant Agarwal.

chevron_right


Python3

filter_none

edit
close

play_arrow

link
brightness_4
code

# Python program to find
# kth common factor
# of two numbers
  
# Returns k'th common
# factor of x and y.
def findKHCF(x,y,k):
  
    # Find smaller of two numbers
    small = min(x, y)
   
    # Count common factors
    # until we either
    # reach small or count
    # becomes k.
    count = 1
    for i in range(2,small+1):
     
        if (x % i==0 and y % i == 0):
            count=count + 1
        if (count == k):
            return i
     
   
    # If we reached small
    return -1
  
# Driver code
  
x = 4
y = 24
k = 3
print(findKHCF(x, y, k))
  
# This code is contributed
# by Anant Agarwal.

chevron_right


C#

filter_none

edit
close

play_arrow

link
brightness_4
code

// C# program to find kth 
// common factor of two numbers
using System;
  
class GFG {
      
// Returns k'th common factor of x and y.
static int findKHCF(int x, int y, int k)
{
      
    // Find smaller of two numbers
    int small = Math.Min(x, y);
  
    // Count common factors until we either
    // reach small or count becomes k.
    int count = 1;
    for (int i = 2; i <= small; i++) 
    {
        if (x % i == 0 && y % i == 0)
            count++;
        if (count == k)
            return i;
    }
  
    // If we reached small
    return -1;
}
  
// Driver code
public static void Main() 
{
    int x = 4, y = 24, k = 3;
    Console.Write(findKHCF(x, y, k));
}
}
  
// This code is contributed by Nitin Mittal.

chevron_right


PHP

filter_none

edit
close

play_arrow

link
brightness_4
code

<?php
// PHP program to find kth 
// common factor of two numbers
  
// Returns k'th common 
// factor of x and y.
function findKCF($x, $y, $k)
{
// Find smaller of two numbers
$small = min($x, $y);
  
// Count common factors until we either
// reach small or count becomes k.
$count = 1;
for ($i = 2; $i <= $small; $i++)
{
    if ($x % $i == 0 && $y % $i == 0)
        $count++;
    if ($count == $k)
        return $i;
}
  
// If we reached small
return -1;
}
  
// Driver code
$x = 4; $y = 24; $k = 3;
echo findKCF($x, $y, $k);
  
// This code is contributed by nitin mittal. 
?>

chevron_right



Output :

4

This article is contributed by Afzal Ansari. If you like GeeksforGeeks and would like to contribute, you can also write an article using contribute.geeksforgeeks.org or mail your article to contribute@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.



My Personal Notes arrow_drop_up

Improved By : nitin mittal



Article Tags :
Practice Tags :


Be the First to upvote.


Please write to us at contribute@geeksforgeeks.org to report any issue with the above content.