Problem #23

This one was rather easy, I just modified the code I used from Problem #21.

#include <iostream>

#define MAX_SIZE_TO_GO_TO 28123

using namespace std;

int sumDivisors (int);
bool isAbundant (int);

int main()
{
    int total = 0;
    int count = 0;
    int allAbundantNumbers[MAX_SIZE_TO_GO_TO];
    bool allNums[MAX_SIZE_TO_GO_TO];

    for (unsigned int i = 0; i < MAX_SIZE_TO_GO_TO; i++)
        allNums[i] = allAbundantNumbers[i] = false;
 
    for (unsigned int i = 0; i < MAX_SIZE_TO_GO_TO; i++)
        if (isAbundant (i))
        {
            allAbundantNumbers[count] = i;
            count++;
        }
 
    for (unsigned int i = 0; i < count; i++)
        for (unsigned int j = 0; j < count; j++)
            if (allAbundantNumbers[i] + allAbundantNumbers[j] <= MAX_SIZE_TO_GO_TO)
                allNums[allAbundantNumbers[i] + allAbundantNumbers[j]] = true;

    for (unsigned int i = 0; i < MAX_SIZE_TO_GO_TO; i++)
        if (allNums[i] == false)
            total += i;

    cout << total << endl;

    system("pause");
    return 0;
}

int sumDivisors (int num)
{
    int total = 0;

    for (unsigned int i = 1; i < static_cast<unsigned int> (num / 2 + 1); i++)
        if (num % i == 0)
            total += i;

    return total;
}

// An abundant number is a number whos proper divisors sum higher than the number it's self
bool isAbundant (int num)
{
    int total = 0;
    total = sumDivisors (num);

    if (total > num)
        return true;
    return false;
}