check_amicable_pair.cpp

Go to the documentation of this file.

#include <cassert>   
#include <iostream>  

namespace math {
int sum_of_divisor(int num) {
    // Variable to store the sum of all proper divisors.
    int sum = 1;
    // Below loop condition helps to reduce Time complexity by a factor of
    // square root of the number.
    for (int div = 2; div * div <= num; ++div) {
        // Check 'div' is divisor of 'num'.
        if (num % div == 0) {
            // If both divisor are same, add once to 'sum'
            if (div == (num / div)) {
                sum += div;
            } else {
                // If both divisor are not the same, add both to 'sum'.
                sum += (div + (num / div));
            }
        }
    }
    return sum;
}

bool are_amicable(int x, int y) {
    return (sum_of_divisor(x) == y) && (sum_of_divisor(y) == x);
}
}  // namespace math

static void tests() {
    assert(math::are_amicable(220, 284) == true);
    assert(math::are_amicable(6368, 6232) == true);
    assert(math::are_amicable(458, 232) == false);
    assert(math::are_amicable(17296, 18416) == true);
    assert(math::are_amicable(18416, 17296) == true);
 
    std::cout << "All tests have successfully passed!" << std::endl;
}

int main() {
    tests();  // perform self-tests implementations
    return 0;
}