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

Recommended: Please try your approach on {IDE} first, before moving on to the solution.

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++

// 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; 
} 

Java

// 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. 

Python3

# 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. 

C#

// 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. 

PHP

<?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.  
?> 

Output :

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.

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Recommended: Please try your approach on {IDE} first, before moving on to the solution.

C++

Java

Python3

C#

PHP

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