Project Euler #9

problem9.cs

//https://projecteuler.net/problem=9
void Main()
{
	int P = 1000;
	
	var t = Enumerable.Range(1,P)
	.Select(a => possibleBC(a, P))
	.SelectMany(_ => _)
	.Where(_=>_.Item2*_.Item2+_.Item3*_.Item3==_.Item1*_.Item1)
	.First();
	
	(t.Item1*t.Item2*t.Item3).Dump();
}

IEnumerable<Tuple<int,int,int>> possibleBC(int a, int P)
{
	return Enumerable.Range(1, P - a)
		.Select(b => new { b = b, c = P - a - b })
		.Where(_=> a<_.b+_.c && _.b<a+_.c && _.c < a+_.b)
		.Select(_=>new Tuple<int,int,int>(a, _.b, _.c));
}