def inside_polygon(x, y, points):
n = len(points)
inside = False
p1x, p1y = points[0]
for i in range(1, n + 1):
p2x, p2y = points[i % n]
if y > min(p1y, p2y):
if y <= max(p1y, p2y):
if x <= max(p1x, p2x):
if p1y != p2y:
xinters = (y - p1y) * (p2x - p1x) / (p2y - p1y) + p1x
if p1x == p2x or x <= xinters:
inside = not inside
p1x, p1y = p2x, p2y
return inside