C++ Program for Common Divisors of Two Numbers

Given two integer numbers, the task is to find the count of all common divisors of given numbers.

Input : a = 12, b = 24
Output: 6
// all common divisors are 1, 2, 3, 
// 4, 6 and 12

Input : a = 3, b = 17
Output: 1
// all common divisors are 1

Input : a = 20, b = 36
Output: 3
// all common divisors are 1, 2, 4

// C++ implementation of program
#include <bits/stdc++.h>
using namespace std;

// Function to calculate gcd of two numbers
int gcd(int a, int b)
{
    if (a == 0)
        return b;
    return gcd(b % a, a);
}

// Function to calculate all common divisors
// of two given numbers
// a, b --> input integer numbers
int commDiv(int a, int b)
{
    // find gcd of a, b
    int n = gcd(a, b);

    // Count divisors of n.
    int result = 0;
    for (int i = 1; i <= sqrt(n); i++) {
        // if 'i' is factor of n
        if (n % i == 0) {
            // check if divisors are equal
            if (n / i == i)
                result += 1;
            else
                result += 2;
        }
    }
    return result;
}

// Driver program to run the case
int main()
{
    int a = 12, b = 24;
    cout << commDiv(a, b);
    return 0;
}

Output:

6

Please refer complete article on Common Divisors of Two Numbers for more details!