Haskell based solution to problem #91 ("Right triangles with integer coordinates") in Project Euler: http://projecteuler.net/problem=91

project-euler-problem-91.hs

reduce x y = (quot x d, quot y d)
	where d = gcd x y
 
right_angle_triangles_in_quadrant n = 
	3 *n * n + 2 * sum others
	where
	others =[min xc yc|
		x1 <- [1..n],
		y1 <- [1..n],
		let (yi,xi) = reduce x1 y1,
		let yc = quot (n-y1) yi,
		let xc = quot x1 xi
	]