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day18.py
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day18.py
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from pathlib import Path
from collections import deque,defaultdict
from functools import lru_cache
from math import inf as INFINITY
import heapq
tunnels = {}
keys = {}
doors = {}
x,y = 0,0
with Path('inputs/input-18-01.txt').open() as f:
for line in f:
for c in line.rstrip():
tunnels[(x,y)] = c
if c not in '.#':
if c == '@':
start = (x,y)
elif c.islower():
keys[(x,y)] = c
else:
doors[(x,y)] = c
x+=1
x=0
y+=1
maxx = max(tunnels, key=lambda x: x[0])[0]
maxy = max(tunnels, key=lambda x: x[1])[1]
minx = min(tunnels, key=lambda x: x[0])[0]
miny = min(tunnels, key=lambda x: x[1])[1]
image = [[ tunnels[(x,y)] for x in range(minx,maxx+1)] for y in range(miny,maxy+1)]
for row in image:
print(*row)
def neighbours(point):
x,y = point
nb = []
for dx,dy in ((0,1),(1,0),(0,-1),(-1,0)):
newx,newy = x+dx,y+dy
try:
c = tunnels[(newx,newy)]
except KeyError:
continue
if c != '#':
yield (newx,newy)
def build_graph():
graph = {}
for pos,val in tunnels.items():
if val not in '#.':
graph[val] = find_adj(pos)
return graph
def find_adj(point):
queue = deque()
visited = {point}
found = []
for n in neighbours(point):
queue.append((1,n))
while queue:
dist, node = queue.popleft()
if node not in visited:
visited.add(node)
val = tunnels[node]
if (node in keys or node in doors) and val not in found:
found.append((val,dist))
continue
for nb in filter(lambda x: x not in visited, neighbours(node)):
queue.append((dist+1,nb))
return found
@lru_cache(2**20)
def distance_for_keys(keys):
return defaultdict(lambda: INFINITY)
@lru_cache(2**20)
def next_keys(pos,found):
queue = []
distance = distance_for_keys(found)
reachable = []
for nb, weight in g[pos]:
queue.append((weight,nb))
heapq.heapify(queue)
while queue:
d,n = heapq.heappop(queue)
if n.islower() and n not in found:
reachable.append((n,d))
continue
if n.lower() not in found:
continue
for nb, w in g[n]:
new_dist = d + w
if new_dist < distance[nb]:
distance[nb] = new_dist
heapq.heappush(queue,(new_dist,nb))
return reachable
@lru_cache(2**20)
def get_steps(sources,need,found=frozenset()):
if need == 0:
return 0
best = INFINITY
for src in sources:
for pos,dist in next_keys(src,found):
newsources = sources.replace(src,pos)
new_found = found | {pos}
new_dist = dist
new_dist += get_steps(newsources,need-1,new_found)
if new_dist < best:
best = new_dist
return best
g=build_graph()
min_steps = get_steps('@',26)
print(min_steps)
for x,y in neighbours(start):
tunnels[(x,y)] = '#'
a,b = start
tunnels[start] = '#'
tunnels[(a-1,a-1)] = '1'
tunnels[(a+1,a-1)] = '2'
tunnels[(a+1,a+1)] = '3'
tunnels[(a-1,a+1)] = '4'
distance_for_keys.cache_clear()
next_keys.cache_clear()
get_steps.cache_clear()
g = build_graph()
min_steps_2 = get_steps('1234', 26)
print(min_steps_2)