private static bool IsTriangleNumber(int s)
{
if (triangleNums.Count() == 0 || triangleNums.Max() < s)
{
triangleNums = TriangleNumberGenerator.Generate().TakeWhile(n => n <= s).ToList();
}
return(triangleNums.Contains(s));
}
public void TestTriangleNumberGenerator()
{
var triangeNumbers = TriangleNumberGenerator.Generate().Take(7).ToArray();
var expected = new[] { 1, 3, 6, 10, 15, 21, 28 };
Assert.AreEqual(expected.Length, triangeNumbers.Length);
for (int i = 0; i < expected.Length; i++)
{
Assert.AreEqual(expected[i], (int)triangeNumbers[i]);
}
}
static void Main(string[] args)
{
// for this problem, we don't need to know the actual divisors, only the number of them
// if you factor a number in to its prime factors, you can calculate the number of divisors
var triangleNumbers = TriangleNumberGenerator.Generate()
.Select(l =>
{
var numberOfFactors = long.Parse(l.ToString()).Factorize().Count();
Console.WriteLine(String.Format("{0} {1}", l, numberOfFactors));
return(new
{
l = l,
numFactors = numberOfFactors
});
})
.Where(l => l.numFactors > 500)
.FirstOrDefault();
Console.WriteLine(triangleNumbers);
Console.ReadKey();
}