def parse_input(string):
points = set()
grid = []
for y, row in enumerate(string.strip("\n").splitlines()):
grid.append([])
for x, character in enumerate(row):
grid[-1].append(character)
if character == ".":
points.add(Point(x, y))
portal_pairs = collections.defaultdict(list)
for y, row in enumerate(grid):
for x, character in enumerate(row):
if not character.isalpha():
continue
character_point = Point(x, y)
neighboring_points = points.intersection(
character_point.neighbors())
if not neighboring_points:
continue
neighboring_point = list(neighboring_points)[0]
direction_to_other_letter = character_point.direction_to(
neighboring_point).inverse_direction()
other_letter_coords = character_point.move_by_direction(
direction_to_other_letter)
other_letter = grid[other_letter_coords.y][other_letter_coords.x]
portal_pairs["".join(sorted(other_letter +
character))].append(neighboring_point)
graph = collections.defaultdict(set)
for p in points:
graph[p].update(points.intersection(p.neighbors()))
for point_pair in portal_pairs.values():
if len(point_pair) < 2:
continue
p1, p2, = point_pair
graph[p1].add(p2)
graph[p2].add(p1)
graph = dict(graph.items())
start, end = portal_pairs["AA"][0], portal_pairs["ZZ"][0]
return graph, start, end
class Explorer:
def __init__(self, tape):
self.tape = tape
self.position = Point(0, 0)
self.graph = collections.defaultdict(set)
self.oxygen = None
def explore(self):
places_to_visit = collections.deque([self.position])
visited = {self.position}
while places_to_visit:
next_point = places_to_visit.pop()
self.move_to(next_point)
unvisited_neighbors = set(self.position.neighbors()) - visited
for neighbor in unvisited_neighbors:
status = self.explore_adjacent_point(neighbor)
if status == StatusCode.Wall:
visited.add(neighbor)
if status in [StatusCode.Step, StatusCode.Oxygen]:
self.graph[self.position].add(neighbor)
self.graph[neighbor].add(self.position)
places_to_visit.append(neighbor)
if status == StatusCode.Oxygen:
self.oxygen = neighbor
visited.add(self.position)
def find_path(self, start, end):
import heapq as h
distances = {start: 0}
heap = [(0, start)]
prev_node = dict()
while end not in prev_node:
weight, node = h.heappop(heap)
unvisited_neighbors = self.graph[node] - distances.keys()
for neighbor in unvisited_neighbors:
prev_node[neighbor] = node
distance = weight + 1
distances[neighbor] = weight
h.heappush(heap, (distance, neighbor))
cur_node = end
path = [end]
while cur_node != start:
previous_node = prev_node[cur_node]
path.append(previous_node)
cur_node = previous_node
return list(reversed(path))[1:]
def distances_from(self, start):
import heapq as h
distances = {start: 0}
heap = [(0, start)]
while heap:
weight, node = h.heappop(heap)
unvisited_neighbors = self.graph[node] - distances.keys()
for neighbor in unvisited_neighbors:
distance = weight + 1
distances[neighbor] = weight
h.heappush(heap, (distance, neighbor))
return distances
def move_direction(self, direction):
input_code = direction_to_int(direction)
status_code = self.tape.run_until_output(provide_input=input_code)[0]
status = StatusCode(status_code)
if status != StatusCode.Wall:
self.position = self.position.displace(*direction.value)
return status
def move_to(self, destination):
if self.position == destination:
return
for point in self.find_path(self.position, destination):
self.move_direction(self.position.direction_to(point))
def explore_adjacent_point(self, point):
direction = self.position.direction_to(point)
status = self.move_direction(direction)
if status != StatusCode.Wall:
self.move_direction(direction.inverse_direction())
return status