def calculate_distance_field(game: Game, source: Pt, target: Pt):
# Calculate and return a distance field from the target, over visited cells only
sentinel = object()
front = deque([source, sentinel])
distfield = {source: 0}
generation = 1
found = False
while front:
p = front.popleft()
if p == sentinel:
if found:
break
assert front
generation += 1
front.append(sentinel)
continue
for d in Action.DIRS.keys():
p2 = p + d
if (p2 not in distfield and game.in_bounds(p2)
and game.is_passable(p2)):
distfield[p2] = generation
front.append(p2)
if p2 == target:
found = True
return distfield
def calculate_spanning_tree(game: Game, pos: Pt):
front = deque([pos])
visited = {pos: Treenode(pos, None)}
found = None
while front:
p = front.popleft()
pnode = visited[p]
for d in Action.DIRS.keys():
p2 = p + d
if (p2 not in visited and game.in_bounds(p2)
and game.is_passable(p2)):
visited[p2] = Treenode(p2, pnode)
pnode.children.append(visited[p2])
front.append(p2)
visited[pos].fill_stats(game)
return visited
