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#!/usr/bin/env python3
import aoc20
import sys
import functools
from collections import defaultdict
@functools.cache
def neighbours3(p):
res = set()
for dx in range(-1, 1+1):
for dy in range(-1, 1+1):
for dz in range(-1, 1+1):
if dx == dy == dz == 0:
continue
res.add((p[0] + dx, p[1] + dy, p[2] + dz))
return res
def pt1(_in):
active = set()
board = defaultdict(lambda: 0)
for y in range(len(_in)):
for x in range(len(_in[y])):
if _in[y][x] == "#":
active.add((x, y, 0))
for n in neighbours3((x, y, 0)):
board[n] += 1
for _ in range(6):
new_board = defaultdict(lambda: 0)
new_active = set()
for p, deg in board.items():
if p in active and 2 <= deg <= 3:
new_active.add(p)
for n in neighbours3(p):
new_board[n] += 1
elif p not in active and deg == 3:
new_active.add(p)
for n in neighbours3(p):
new_board[n] += 1
board = new_board
active = new_active
return(len(active))
@functools.cache
def neighbours4(p):
res = set()
for dx in range(-1, 1+1):
for dy in range(-1, 1+1):
for dz in range(-1, 1+1):
for dw in range(-1, 1+1):
if dx == dy == dz == dw == 0:
continue
res.add((p[0] + dx, p[1] + dy, p[2] + dz, p[3] + dw))
return res
def pt2(_in):
active = set()
board = defaultdict(lambda: 0)
for y in range(len(_in)):
for x in range(len(_in[y])):
if _in[y][x] == "#":
active.add((x, y, 0, 0))
for n in neighbours4((x, y, 0, 0)):
board[n] += 1
for _ in range(6):
new_board = defaultdict(lambda: 0)
new_active = set()
for p, deg in board.items():
if p in active and 2 <= deg <= 3:
new_active.add(p)
for n in neighbours4(p):
new_board[n] += 1
elif p not in active and deg == 3:
new_active.add(p)
for n in neighbours4(p):
new_board[n] += 1
board = new_board
active = new_active
return(len(active))
if __name__ == "__main__":
input = aoc20.read_input(sys.argv[1:], 17)
print(pt1(input))
print(pt2(input))
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