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import collections
import heapq as heap
import sys
def neighbours(p):
return [(p[0]+1, p[1]), (p[0]-1, p[1]), \
(p[0], p[1]+1), (p[0], p[1]-1)]
def draw(map, pos=None, keys={}, doors={}, path={}, visited={}, dead=set()) -> str:
min_x=max_x=min_y=max_y = 0
for p in map:
min_x = min(p[0], min_x)
max_x = max(p[0], max_x)
min_y = min(p[1], min_y)
max_y = max(p[1], max_y)
s = ""
for y in range(min_y-1, max_y+2):
s += "\n"
for x in range(min_x-1, max_x+2):
point = (x, y)
if pos is not None and point == pos:
s += "@"
elif point in keys:
s += keys[point]
elif point in doors:
s += doors[point]
elif point in path:
s += "\u2591"
elif point in visited:
s += "."
elif point in dead:
s += "X"
elif point in map:
if map[point] == "#":
s += "\u2588"
else:
s += " "
else:
s += "."
return s
def avail(map, start, items, dead, ignore=set()):
visited = set()
avail = []
q = collections.deque()
q.append((0, start))
while len(q) > 0:
cur = q.popleft()
dist = cur[0]
pos = cur[1]
if pos in items and pos != start:
avail.append((dist, pos, items[pos]))
continue
for n in neighbours(pos):
if (n in map and map[n] == "#") or n in dead or n in visited or n in ignore:
continue
visited.add(n)
q.append((dist+1, n))
return avail
def avail_keys(map, keys, doors, graph, start, keys_left, unlocked_doors):
visited = set()
avail = []
h = []
heap.heappush(h, (0, start))
while len(h) > 0:
dist, cur_key = heap.heappop(h)
if cur_key != start and cur_key.islower() and cur_key in keys_left:
avail.append((dist, cur_key))
continue
for n in graph[cur_key]:
if n[0].isupper() and n[0] not in unlocked_doors:
continue
if n[0] in visited:
continue
visited.add(n[0])
heap.heappush(h, (dist + n[1], n[0]))
return avail
def pt1(input):
map = {}
map_keys = {}
map_doors = {}
map_keys_doors = {}
walls = set()
tiles = set()
for y in range(len(input)):
for x in range(len(input[y].strip())):
c = input[y][x]
p = (x,y)
if c == "@":
start = p
map[p] = "."
elif c.isalpha():
if c.isupper():
map_doors[p] = c
else:
map_keys[p] = c
map[p] = "."
elif c == "#":
walls.add(p)
map[p] = c
elif c == ".":
tiles.add(p)
map[p] = c
map_keys_doors.update(map_keys)
map_keys_doors.update(map_doors)
dead = set()
for _ in range(10):
#TODO repeat until no further changes are done
ends = set()
intersections = set()
for tile in tiles:
num_walls = 0
for n in neighbours(tile):
if n in walls or n in dead:
num_walls += 1
if num_walls == 3:
ends.add(tile)
elif num_walls < 2:
intersections.add(tile)
for end in ends:
cur = end
while cur not in intersections and cur not in map_keys and cur not in map_doors:
dead.add(cur)
if cur in tiles:
tiles.remove(cur)
for n in neighbours(cur):
if n not in walls and n not in dead:
cur = n
break
paths = {} # every path available between a door and a key
start_paths = {} # every path available from the starting point
graph = {} # {node: [children as tuples with name and distance]}
for ent, s in map_keys_doors.items():
for a in avail(map, ent, map_keys_doors, dead):
paths[(s, a[2])] = a[0]
graph[s] = graph.get(s, []) + [(a[2], a[0])]
for a in avail(map, start, map_keys, dead, map_doors):
start_paths[("@", map_keys[a[1]])] = a[0]
h = []
for path, dist in start_paths.items():
cur = path[1]
keys_left = set(map_keys.values()).copy()
keys_left.remove(cur)
unlocked = set()
unlocked.add(cur.upper())
key_path = [cur]
heap.heappush(h, (dist, cur, keys_left, unlocked, key_path))
best = len(map_keys)
seen = set()
while True:
dist, key, keys_left, unlocked, key_path = heap.heappop(h)
if (frozenset(key_path), key) in seen:
continue
seen.add((frozenset(key_path), key))
if len(keys_left) == 0:
return dist
if len(keys_left) < best:
best = len(keys_left)
for new_dist, new_key in avail_keys(map, map_keys, map_doors, graph, key, keys_left, unlocked):
new_keys_left = keys_left.copy()
new_keys_left.remove(new_key)
new_unlocked = unlocked.copy()
new_unlocked.add(new_key.upper())
new_key_path = key_path.copy()
new_key_path.append(new_key)
heap.heappush(h, (dist + new_dist, new_key, new_keys_left, new_unlocked, new_key_path))
if __name__ == "__main__":
print(pt1(open("../input/18-1", "r").readlines()))
print(pt2(open("../input/18-2", "r").readlines()))
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