count_right_angles.py

def get_length_square(p1, p2):
    return (p1[0]-p2[0])**2 + (p1[1] - p2[1])**2

def check_angle(p1, p2, p3):
    return get_length_square(p1, p3) == get_length_square(p1, p2) + get_length_square(p2, p3)

def count_right_angles(coords):
    count = 0
    if check_angle(coords[0],coords[1],coords[2]):
    	count = count + 1
    if check_angle(coords[1],coords[2],coords[3]):
    	count = count + 1
    if check_angle(coords[2],coords[3],coords[0]):
    	count = count + 1
    if check_angle(coords[3],coords[0],coords[1]):
    	count = count + 1
    return count

if __name__ == '__main__':
    test_data = [[-1, 0], [-1, 4], [2, 4], [4, 1]]
    print(count_right_angles(test_data))