My Advent of Code solutions in Python.
kevinyap.ca/2019/12/going-fast-in-advent-of-code/
advent-of-code
python
Add 2022/23
+63
+63
2022/day23.py
+63
2022/day23.py
···
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import fileinput
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from collections import defaultdict
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from utils import Point, N, NE, E, SE, S, SW, W, NW, min_max_xy
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BOARD = {}
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for y, line in enumerate(fileinput.input()):
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for x, c in enumerate(line.strip()):
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BOARD[Point(x, y)] = c
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# N and S are switched from the problem statement because of
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# the convention of using +y -> N in my utils, which does have
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# an effect on the interaction between elves in this problem.
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CHECKS = [
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[[S, SE, SW], S],
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[[N, NE, NW], N],
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[[W, NW, SW], W],
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[[E, NE, SE], E],
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]
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for i in range(100000):
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proposal = defaultdict(list)
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for p, c in BOARD.items():
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if c == '#':
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# If elf has no neighbours in all 8 directions, don't consider moving.
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if not any(BOARD.get(n) == '#' for n in p.neighbours_8()):
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continue
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# Add elf's proposed location to `proposal`.
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for d in range(4):
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checks, move = CHECKS[(i + d) % 4]
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if any(BOARD.get(p + c, ' ') == '#' for c in checks):
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continue
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proposal[p + move].append(p)
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break
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for new_loc in proposal:
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elves = proposal[new_loc]
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# If only one elf wants to move there, they can move (and vacate their old spot).
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if len(elves) == 1:
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BOARD[elves[0]] = '.'
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BOARD[new_loc] = '#'
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# Answer to part 1, compute number of empty squares within the bounds.
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if i == 9:
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elves = [p for p in BOARD if BOARD[p] == '#']
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min_x, max_x, min_y, max_y = min_max_xy(elves)
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blanks = 0
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for y in range(min_y, max_y + 1):
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for x in range(min_x, max_x + 1):
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p = Point(x, y)
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if BOARD.get(p) != '#':
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blanks += 1
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print("Part 1:", blanks)
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# Empty proposal list -> no elves moved, the answer to part 2.
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if len(proposal) == 0:
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print("Part 2:", i + 1)
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break