110 lines
3.3 KiB
Python
110 lines
3.3 KiB
Python
from collections import defaultdict
|
|
from string import ascii_uppercase
|
|
|
|
from grid import Grid
|
|
|
|
|
|
def main():
|
|
with open("day20.txt") as input_file:
|
|
lines = [l.rstrip() for l in input_file.readlines()]
|
|
maze = Maze(lines, value_factory=str)
|
|
|
|
maze.find_portals()
|
|
maze.dumb_print()
|
|
min_steps = maze.count_min_steps(maze.entry, maze.exit)
|
|
print("Min steps:", min_steps)
|
|
|
|
|
|
class Maze(Grid):
|
|
|
|
TILE_PATH = "."
|
|
TILE_WALL = "#"
|
|
|
|
ENTRY_DG = "AA"
|
|
EXIT_DG = "ZZ"
|
|
|
|
def __init__(self, lines, *args, **kwargs):
|
|
super().__init__(*args, **kwargs)
|
|
self.entry = None
|
|
self.exit = None
|
|
self.portals = {}
|
|
for y, line in enumerate(lines):
|
|
for x, value in enumerate(line):
|
|
self.setv(x, y, value)
|
|
|
|
def find_portals(self):
|
|
portals = defaultdict(list)
|
|
for x, y, v in list(self.values_gen()):
|
|
if v in ascii_uppercase:
|
|
rv = self.getv(x + 1, y)
|
|
if rv and rv in ascii_uppercase:
|
|
rrv = self.getv(x + 2, y)
|
|
portal_pos = (x + 2, y) if rrv == Maze.TILE_PATH else (x - 1, y)
|
|
portals[v + rv].append(portal_pos)
|
|
continue
|
|
dv = self.getv(x, y + 1)
|
|
if dv and dv in ascii_uppercase:
|
|
ddv = self.getv(x, y + 2)
|
|
portal_pos = (x, y + 2) if ddv == Maze.TILE_PATH else (x, y - 1)
|
|
portals[v + dv].append(portal_pos)
|
|
for n, p in portals.items():
|
|
if n == "AA":
|
|
self.entry = p[0]
|
|
elif n == "ZZ":
|
|
self.exit = p[0]
|
|
else:
|
|
self.portals[p[0]] = p[1]
|
|
self.portals[p[1]] = p[0]
|
|
|
|
def dumb_print(self):
|
|
for y, row in self.g.items():
|
|
for x, v in row.items():
|
|
if (x, y) in self.portals:
|
|
v = "░"
|
|
if (x, y) in (self.entry, self.exit):
|
|
v = "▒"
|
|
print(v, end="")
|
|
print()
|
|
|
|
def bfs(self, start, end):
|
|
discovered = Grid(value_factory=bool)
|
|
discovered.setv(start[0], end[1], True)
|
|
parents = {}
|
|
q = [start]
|
|
while q:
|
|
pos = q.pop(0)
|
|
if pos == end:
|
|
return parents
|
|
nears = self.near_objects(pos)
|
|
for near_pos, near_tile in nears.items():
|
|
if near_tile != Maze.TILE_PATH:
|
|
continue
|
|
if discovered.getv(near_pos[0], near_pos[1]):
|
|
continue
|
|
discovered.setv(near_pos[0], near_pos[1], True)
|
|
parents[near_pos] = pos
|
|
q.append(near_pos)
|
|
return None
|
|
|
|
def count_min_steps(self, start, end):
|
|
parents = self.bfs(start, end)
|
|
count = 0
|
|
pos = end
|
|
while pos != start:
|
|
pos = parents[pos]
|
|
count += 1
|
|
if pos in self.portals: # One more step to traverse portal.
|
|
count += 1
|
|
return count
|
|
|
|
def near_objects(self, p):
|
|
nears = super().near_objects(p)
|
|
for near in list(nears):
|
|
if near in self.portals:
|
|
nears[self.portals[near]] = Maze.TILE_PATH
|
|
return nears
|
|
|
|
|
|
if __name__ == "__main__":
|
|
main()
|