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python-aoc-2020/day20/part1-v2.py
2020-12-28 22:18:55 +01:00

54 lines
1.5 KiB
Python

#!/usr/bin/env python3
from collections import defaultdict
from functools import reduce
import numpy as np
lines = (x.strip() for x in open("input.txt"))
rotations = [(t, r) for t in (True, False) for r in range(4)]
tiles = {}
borders = defaultdict(set)
def add_tile(num, tile):
global tiles, borders
tiles[num] = tile
for transpose, rotate in rotations:
view = np.rot90(tile.T if transpose else tile, rotate)
edge = np.packbits(view[0])
edge = edge[0] * 4 + edge[1] // 64
borders[edge].add(num)
for line in lines:
if line.startswith("Tile"):
num = int(line[5:-1])
tile = np.zeros((10, 10), dtype=np.int16)
lnr = 0
elif line == "":
add_tile(num, tile)
else:
a = np.array([(0 if x == '.' else 1) for x in line], dtype=np.int16)
tile[lnr] = a
lnr += 1
add_tile(num, tile)
# every border matches only once
print("sum joints", sum(1 for key, val in borders.items() if len(val) > 1))
print("should joints", (len(tiles)-np.sqrt(len(tiles))) * 2)
print("sum outer", sum(1 for key, val in borders.items() if len(val) == 1))
print("should outer", np.sqrt(len(tiles)) * 4)
print("cnt tiles", len(tiles))
print("multi matches", sum(1 for key, val in borders.items() if len(val) > 2))
# find corners
edges = defaultdict(int)
for key, val in borders.items():
if len(val) == 1:
for item in val:
edges[item] += 1
print(reduce(lambda a, b: a*b, (key for key, val in edges.items() if val == 4), 1))