public string GetSolution()
{
var totalSum = 0;
for (int i = 2; i < 10000; i++)
{
var divisorsSum = Factors.GetProperDivisors(i).Sum();
var otherDivisorsSum = Factors.GetProperDivisors(divisorsSum).Sum();
if (i != divisorsSum && otherDivisorsSum < 10000 && otherDivisorsSum == i)
{
totalSum += i;
}
}
return(totalSum.ToString());
}
public string GetSolution()
{
var abundantNumbers = Enumerable.Range(1, limit).Where(n => Factors.GetProperDivisors(n).Sum() > n).ToArray();
var abundantSums = new Dictionary <int, bool>();
for (int i = 0; i < abundantNumbers.Length; i++)
{
for (int j = i; j < abundantNumbers.Length; j++)
{
var sum = abundantNumbers[i] + abundantNumbers[j];
if (sum > limit)
{
break;
}
abundantSums[sum] = true;
}
}
return(Enumerable.Range(1, limit).Except(abundantSums.Keys).Sum().ToString());
}
