C++ Exercises: Check two numbers are Amicable numbers or not

C++ Numbers: Exercise-28 with Solution

Write a C++ program to check two numbers are Amicable numbers or not.

Sample Solution:

C++ Code :

#include <bits/stdc++.h> // Include all standard C++ libraries

using namespace std; // Using the standard namespace

int ProDivSum(int n) // Function to calculate the sum of proper divisors of a number 'n'
{
    int sum = 1; // Initialize sum with 1 (as 1 is a divisor for all numbers)
    for (int i = 2; i <= sqrt(n); i++) // Loop through numbers from 2 to square root of 'n'
    {
        if (n % i == 0) // Check if 'i' is a divisor of 'n'
        {
            sum += i; // Add 'i' to the sum

            // If 'n' is divisible by 'i' but not equal to 'i', add the corresponding divisor to the sum
            if (n / i != i)
                sum += n / i;
        }
    }
    return sum; // Return the sum of proper divisors
}

bool chkAmicable(int a, int b) // Function to check if two numbers 'a' and 'b' are amicable pairs
{
    return (ProDivSum(a) == b && ProDivSum(b) == a); // Return true if the sum of proper divisors of 'a' equals 'b' and vice versa
}

int main()
{
    int n, i, j, ctr, nm1, nm2; // Declare integer variables
    cout << "\n\n Check whether two numbers are Amicable pairs or not: \n"; // Display a message
    cout << "\n Sample: (220, 284), (1184, 1210), (2620, 2924).. \n";
    cout << " --------------------------------------------------------\n";
    cout << " Input the 1st number : ";
    cin >> nm1; // Input the first number
    cout << " Input the 2nd number : ";
    cin >> nm2; // Input the second number

    if (chkAmicable(nm1, nm2)) // Check if the input numbers are amicable pairs
        cout << " The given numbers are an Amicable pair." << endl; // Display if they are amicable pairs
    else
        cout << " The given numbers are not an Amicable pair." << endl; // Display if they are not amicable pairs

    return 0; // Exit the program
}

Sample Output:

Check whether two numbers are Amicable pairs or not:                  
                                                                       
 Sample: (220, 284), (1184, 1210), (2620, 2924)..                      
 --------------------------------------------------------              
 Input the 1st number : 220                                            
 Input the 2nd number : 284                                            
 The given numbers are an Amicable pair.

Flowchart:

C++ Code Editor:

Contribute your code and comments through Disqus.

Previous: Write a program in C++ to find Duck Numbers between 1 to 500.
Next: Write a program in C++ to count the Amicable pairs in an array.