Project Euler 102

problem102.rb

def same_side p1, p2, p3, p4
	cp1 = cross_product p4-p3, p1-p3
	cp2 = cross_product p4-p3, p2-p3
	dot_product(cp1, cp2) >=0
end

# is the point p in the triangle
def point_in_triangle p=Vector[0,0,0], a, b, c
	same_side(p, a, b, c) && same_side(p, b, a, c) && same_side(p, c, a, b)
end