## CheckIO: Shooting range

```import math

def calc_hitpoint(crd1, direction1, crd2, direction2):
(a, b), (c, d) = crd1, crd2
(d1, d2), (d3, d4) = direction1, direction2
if d1 * d4 == d2 * d3:
return None, None  # parralel lines
k = ((b - d) * d3 - (a - c) * d4) / (d1 * d4 - d2 * d3)
return (a + d1 * k, b + d2 * k), k

def calc_equation(crd1, crd2):
a = (crd1[1] - crd2[1]) / (crd1[0] - crd2[0])
b = crd1[1] - a * crd1[0]
return lambda x: a * x + b

def shot(wall1, wall2, shot_point, later_point):
avg = lambda x, y: (x + y) / 2
direction = lambda crd1, crd2: tuple((x[0] - x[1]) for x in zip(crd1, crd2))
distance = lambda crd1, crd2: math.sqrt(sum((x[0] - x[1]) ** 2 for x in zip(crd1, crd2)))

ballistic, wall = direction(later_point, shot_point), direction(wall2, wall1)
hit_point, k = calc_hitpoint(shot_point, ballistic, wall1, wall)

if k and k > 0 and all(
sorted(w)[0] <= hit_point[i] <= sorted(w)[1]
for i, w in enumerate(zip(wall1, wall2))
):
center = tuple(avg(c1, c2) for c1, c2 in zip(wall1, wall2))
score = calc_equation((0, 100), (distance(wall1, wall2) / 2, 0))
return round(score(distance(center, hit_point)))
else:
return -1

if __name__ == '__main__':
#These "asserts" using only for self-checking and not necessary for auto-testing
assert shot((2, 2), (5, 7), (11, 2), (8, 3)) == 100, "1st case"
assert shot((2, 2), (5, 7), (11, 2), (7, 2)) == 0, "2nd case"
assert shot((2, 2), (5, 7), (11, 2), (8, 4)) == 29, "3th case"
assert shot((2, 2), (5, 7), (11, 2), (9, 5)) == -1, "4th case"
assert shot((2, 2), (5, 7), (11, 2), (10.5, 3)) == -1, "4th case again"```

http://www.checkio.org/mission/shoot-range/