87 lines
2.6 KiB
Python
87 lines
2.6 KiB
Python
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from helpers import *
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lines = read_day(23).split('\n')
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sample_lines = '''
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....#..
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..###.#
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#...#.#
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.#...##
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#.###..
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##.#.##
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.#..#..
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'''.strip().split('\n')
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def get_intention(round, elves, x, y):
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adj_nw = (x-1,y-1) in elves
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adj_w = (x-1,y) in elves
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adj_sw = (x-1,y+1) in elves
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adj_n = (x,y-1) in elves
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adj_s = (x,y+1) in elves
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adj_ne = (x+1,y-1) in elves
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adj_e = (x+1,y) in elves
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adj_se = (x+1,y+1) in elves
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if adj_nw or adj_n or adj_ne or adj_w or adj_e or adj_sw or adj_s or adj_se:
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for i in range(4):
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direction = (round + i) % 4
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if (direction == 0) and not (adj_n or adj_nw or adj_ne):
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return (x,y-1) # move north
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if (direction == 1) and not (adj_s or adj_sw or adj_se):
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return (x,y+1) # move south
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if (direction == 2) and not (adj_w or adj_nw or adj_sw):
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return (x-1,y) # move west
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if (direction == 3) and not (adj_e or adj_ne or adj_se):
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return (x+1,y) # move east
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return (x,y) # no movement
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def simulate(lines: list[str], rounds: int = 10) -> set[tuple[int,int]]:
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# position = np.array([[c=='#' for c in line] for line in lines], dtype=np.bool8)
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elves = set()
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for row, line in enumerate(lines):
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for col, c in enumerate(line):
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if c == '#':
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elves.add((col, row))
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for round in range(rounds):
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if round == 10:
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print(f'*** Part 1: ground tiles after round #10: {get_rect(elves)} ***')
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# else:
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# print(f'\tground tiles before round #{round+1}: {get_rect(elves)}')
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# print(f'performing round #{round+1}')
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next_elves = {}
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for x,y in sorted(elves, key=lambda p: (p[1], p[0])):
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intention = get_intention(round, elves, x, y)
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# print(f'{x,y} wants to move to {intention}')
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next_elves[intention] = next_elves.get(intention, []) + [(x,y)]
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old_elves = elves
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elves = set()
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for position, elf_intentions in next_elves.items():
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if len(elf_intentions) == 1:
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elves.add(position)
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else:
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# print(f'conflict: {len(elf_intentions)} elves tried to move to {position}')
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elves |= set(elf_intentions) # neither move
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if old_elves == elves:
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print(f'*** Part 2: No elves moved in round #{round+1} ***')
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break
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print(f'Final ground tiles: {get_rect(elves)}')
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return elves
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def get_rect(elves: set[tuple[int,int]]):
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x0, x1, y0, y1 = None, None, None, None
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for x,y in elves:
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if x0 is None or x < x0:
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x0 = x
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if x1 is None or x > x1:
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x1 = x
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if y0 is None or y < y0:
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y0 = y
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if y1 is None or y > y1:
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y1 = y
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# print(f'Elves in rectangle from x:{x0}~{x1}, y:{y0}~{y1}')
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# for y in range(y0, y1+1):
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# print(''.join(('#' if (x,y) in elves else '.' for x in range(x0,x1+1))))
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rect_size = (x1-x0+1)*(y1-y0+1) # inclusive
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return rect_size - len(elves)
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simulate(sample_lines, 100)
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simulate(lines, 100000)
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