My Advent of Code solutions in Python.
kevinyap.ca/2019/12/going-fast-in-advent-of-code/
advent-of-code
python
Add 2021/11
+52
+52
2021/day11.py
+52
2021/day11.py
···
1
+
import copy
2
+
import fileinput
3
+
from utils import Point
4
+
5
+
board = {}
6
+
for y, line in enumerate(fileinput.input()):
7
+
for x, c in enumerate(line.strip()):
8
+
board[Point(x, y)] = int(c)
9
+
10
+
11
+
part_1 = 0
12
+
13
+
for i in range(10000000):
14
+
next_state = copy.copy(board)
15
+
16
+
for pos, val in next_state.items():
17
+
next_state[pos] = val + 1
18
+
19
+
flashed = set()
20
+
while True: # when steady state
21
+
updated = False
22
+
23
+
for pos, val in next_state.items():
24
+
# Flash!
25
+
if next_state[pos] > 9 and pos not in flashed:
26
+
# Increment all 8 neighbours
27
+
for n in pos.neighbours_8():
28
+
if n not in next_state:
29
+
continue
30
+
31
+
next_state[n] = next_state[n] + 1
32
+
33
+
flashed.add(pos)
34
+
part_1 += 1
35
+
updated = True
36
+
37
+
if not updated:
38
+
break
39
+
40
+
if len(flashed) == len(next_state):
41
+
print "Part 2:", i + 1
42
+
break
43
+
44
+
# Reset all >9s to 0
45
+
for pos, val in next_state.items():
46
+
if val > 9:
47
+
next_state[pos] = 0
48
+
49
+
board = next_state
50
+
51
+
if i == 99:
52
+
print "Part 1:", part_1