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

87 lines
2.7 KiB
Python

#!/usr/bin/env python3
import numpy as np
l = -1
def calc(line):
x = 0
for elem in line:
x = x*2 + elem
return x
def solve(arr, pos, s, left_keys):
global l
if pos >= s*s:
return True
idx = (pos // s * 2, pos % s * 2)
if l != len(left_keys):
print("-"*pos, pos, len(left_keys), idx)
l = len(left_keys)
top = (idx[0], idx[1]-1) if idx[1] > 0 else None
bottom = (idx[0], idx[1]+1) if idx[1] < s else None
left = (idx[0]-1, idx[1]) if idx[0] > 0 else None
right = (idx[0]+1, idx[1]) if idx[0] < s else None
for key in left_keys:
new_keys = left_keys.copy()
new_keys.discard(key)
for transpose, rotate in ([(False, 0)] if pos == 0 else rotations):
view = np.rot90(tiles[key].T if transpose else tiles[key], rotate)
if (top is None or arr[top] == -1 or arr[top] == calc(view[0])) and \
(bottom is None or arr[bottom] == -1 or arr[bottom] == calc(view[-1])) and \
(left is None or arr[left] == -1 or arr[left] == calc(view[:, 0])) and \
(right is None or arr[right] == -1 or arr[right] == calc(view[:, -1])):
arr[idx] = key
if right is not None:
arr[right] = calc(view[:, -1])
if bottom is not None:
arr[bottom] = calc(view[-1])
#print("B", arr)
#print("bef", pos)
if pos % s == 0:
p = pos // s + 1
p = p if p != s else p+s-1
else:
p = pos + s - 1
p = p if p <= s*s-1 else (p-s*s+3)*s-1
#print("change", p)
if solve(arr, p, s, new_keys):
return True
arr[idx] = -1
if right is not None:
arr[right] = -1
if bottom is not None:
arr[bottom] = -1
return False
lines = (x.strip() for x in open("input.txt"))
rotations = [(t, r) for t in (True, False) for r in range(4)]
tiles = {}
num = None
tile = None
lnr = None
for line in lines:
if line.startswith("Tile"):
num = int(line[5:-1])
tile = np.zeros((10, 10), dtype=np.int8)
lnr = 0
elif line == "":
tiles[num] = tile
else:
a = np.array([(0 if x == '.' else 1) for x in line], dtype=np.int8)
tile[lnr] = a
lnr += 1
tiles[num] = tile
size = int(np.sqrt(len(tiles)))
positioning = -np.ones((size*2-1, size*2-1), dtype=np.int64)
print(positioning.shape)
if solve(positioning, 0, size, set(tiles.keys())):
print(positioning)
print(positioning[0, 0]*positioning[-1, 0]*positioning[0, -1]*positioning[-1, -1])
else:
print("fail")