2020/python/day20.py

244 lines
5.2 KiB
Python

import fileinput
from pprint import pprint
import itertools
from copy import deepcopy
N = 10
#
# Parse the input
#
current_tile = None
tiles = []
for line in fileinput.input():
line = line.strip()
if not line:
continue
if line.startswith("Tile "):
if current_tile:
assert len(current_tile) == N
tiles.append((current_id, current_tile))
current_id = int(line[5:-1])
current_tile = []
else:
assert len(line) == N
current_tile.append(list(line))
assert len(current_tile) == N
tiles.append((current_id, current_tile))
def aligns_right(left, right):
return all(left[y][-1] == right[y][0] for y in range(len(left)))
def aligns_bottom(top, bottom):
return all(top[-1][x] == bottom[0][x] for x in range(len(top)))
def aligns(apos, b):
ax, ay = apos
_, a = kek[(ax, ay)]
if aligns_right(a, b):
return 1, 0
if aligns_right(b, a):
return -1, 0
if aligns_bottom(a, b):
return 0, 1
if aligns_bottom(b, a):
return 0, -1
return None
def rotate(a):
output = deepcopy(a)
for y in range(len(a)):
for x in range(len(a)):
output[-1 - x][y] = a[y][x]
return output
def flip(a):
output = [None] * len(a)
for y in range(len(a)):
output[y] = list(reversed(a[y]))
return output
def rotate_align(a_pos, b):
"""
Rotates and flips a and checks if it aligns for every possible orientation.
"""
if d := aligns(a_pos, b):
return b, d
bf = flip(b)
if d := aligns(a_pos, bf):
return bf, d
b = rotate(b)
if d := aligns(a_pos, b):
return b, d
bf = flip(b)
if d := aligns(a_pos, bf):
return bf, d
b = rotate(b)
if d := aligns(a_pos, b):
return b, d
bf = flip(b)
if d := aligns(a_pos, bf):
return bf, d
b = rotate(b)
if d := aligns(a_pos, b):
return b, d
bf = flip(b)
if d := aligns(a_pos, bf):
return bf, d
return None, None
positions = {tiles[0][0]: ((0, 0), tiles[0][1])}
kek = {(0, 0): tiles[0]}
while len(positions) != len(tiles):
for a_id, _ in tiles:
((a_x, a_y), a_tile) = positions.get(a_id, ((None, None), None))
if not a_tile:
continue
for b_id, b_tile in tiles:
if b_id in positions or a_id == b_id:
continue
transformed, dpos = rotate_align((a_x, a_y), b_tile)
if dpos is not None:
dx, dy = dpos
b_x = a_x + dx
b_y = a_y + dy
positions[b_id] = (b_x, b_y), transformed
kek[(b_x, b_y)] = b_id, transformed
min_y = min(y for ((_, y), _) in positions.values())
max_y = max(y for ((_, y), _) in positions.values())
min_x = min(x for ((x, _), _) in positions.values())
max_x = max(x for ((x, _), _) in positions.values())
tilemap = {pos: (id, tile) for id, (pos, tile) in positions.items()}
bl, _ = tilemap[(min_x, min_y)]
br, _ = tilemap[(max_x, min_y)]
tl, _ = tilemap[(min_x, max_y)]
tr, _ = tilemap[(max_x, max_y)]
print("Part 1:", tl * tr * bl * br)
def is_snek(b, x, y):
for (x_, y_) in (
(0, 0),
(1, 1),
(4, 1),
(5, 0),
(6, 0),
(7, 1),
(10, 1),
(11, 0),
(12, 0),
(13, 1),
(16, 1),
(17, 0),
(18, 0),
(18, -1),
(19, 0),
):
try:
if b[y_ + y][x_ + x] == ".":
return False
except:
return False
return True
def find_sneks(b):
sneks = []
for (x, y) in itertools.product(range(8 * 12), repeat=2):
if is_snek(b, x, y):
print(x, y, "is snek")
sneks.append((x, y))
return sneks
def rotate_find_sneks(b):
if d := find_sneks(b):
return b, d
bf = flip(b)
if d := find_sneks(bf):
return bf, d
b = rotate(b)
if d := find_sneks(b):
return b, d
bf = flip(b)
if d := find_sneks(bf):
return bf, d
b = rotate(b)
if d := find_sneks(b):
return b, d
bf = flip(b)
if d := find_sneks(bf):
return bf, d
b = rotate(b)
if d := find_sneks(b):
return b, d
bf = flip(b)
if d := find_sneks(bf):
return bf, d
def remove_snek(snek):
# :(
(x, y) = snek
for (x_, y_) in (
(0, 0),
(1, 1),
(4, 1),
(5, 0),
(6, 0),
(7, 1),
(10, 1),
(11, 0),
(12, 0),
(13, 1),
(16, 1),
(17, 0),
(18, 0),
(18, -1),
(19, 0),
):
big_chungus[y + y_][x + x_] = '.'
chungus = [["."] * 8 * (max_x - min_x + 1) for _ in range(8 * (max_y - min_y + 1))]
for (x, y), (id, tile) in tilemap.items():
x_ = (x - min_x) * 8
y_ = (y - min_y) * 8
for i, row in enumerate(tile[1:-1]):
for j, c in enumerate(row[1:-1]):
chungus[i + y_][j + x_] = c
# for y, row in enumerate(chungus):
# print("".join(row))
big_chungus, sneks = rotate_find_sneks(chungus)
for snek in sneks:
remove_snek(snek)
part2 = 0
for row in big_chungus:
for c in row:
if c == "#":
part2 += 1
print("Part 2:", part2)