def a_star(n, start, goal, obstacles):
priority = lambda p: len(p) + puz.manhattan_dist(p[-1], goal)
visited = set()
frontier = list()
q.heappush(frontier, (priority([start]), [start]))
while frontier:
_, path = q.heappop(frontier)
if path[-1] == goal:
return path
if not path[-1] in visited:
visited.add(path[-1])
walkable_neighbors = [nb for nb in puz.direct_neighbors(path[-1])
if puz.on_field((n, n), nb) and nb not in obstacles] # TODO
for p in [path + [n] for n in walkable_neighbors]:
q.heappush(frontier, (priority(p), p))
return None
def test_manhattan_dist(self):
self.assertEqual(p.manhattan_dist((0, 0), (1, 1)), 2)
