public static void Main()
{
WriteLine("Problem 23");
long answer = Problem23.Solve();
WriteLine($"answer = {answer}");
}
static void Main(string[] args)
{
Problem23 prog = new Problem23();
BitArray abundantNumbers = new BitArray(28124);
BitArray test = new BitArray(28124);
//Console.WriteLine(prog.isPerfectNumber(28));
//Console.WriteLine(prog.isPerfectNumber(12));
int sumtotal = 0;
for (int i = 2; i <= 28123; i++)
{
if (prog.isAbundantNumber(i))
{
abundantNumbers[i] = true;
}
}
for (int i = 2; i <= 28123; i++)
{
if (abundantNumbers[i])
{
for (int j = 2; j <= 28123; j++)
{
if (i + j > 28123)
{
break;
}
if (abundantNumbers[j])
{
int sum = i + j;
test[sum] = true;
}
}
}
}
// copy paste got me
for (int i = 1; i <= 28123; i++)
{
if (!test[i])
{
sumtotal += i;
}
}
Console.WriteLine("Answer = " + sumtotal);
Console.ReadKey();
}