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162 lines
5.0 KiB
Python
162 lines
5.0 KiB
Python
import itertools
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import numpy
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from . import SeparateRunner
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def parse_input(data: str) -> tuple[numpy.array, str]:
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grid, steps = data.split("\n\n")
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grid_split = numpy.array([list(line) for line in grid.split("\n")])
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steps = "".join(steps.split("\n"))
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return grid_split, steps
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def convert_dir(c: str) -> tuple[int, int]:
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match c:
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case "^":
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return 0, -1
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case ">":
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return 1, 0
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case "<":
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return -1, 0
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case "v":
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return 0, 1
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case other:
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raise ValueError(f"Invalid movement: {other}")
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class DayRunner(SeparateRunner):
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@classmethod
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def part1(cls, input: str) -> None:
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grid, steps = parse_input(input)
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y, x = numpy.where(grid == "@")
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x, y = x[0], y[0]
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for c in steps:
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dx, dy = convert_dir(c)
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match grid[y + dy, x + dx]:
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case "#":
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continue
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case "O":
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crashed = False
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for dist in itertools.count(2):
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match grid[y + dist * dy, x + dist * dx]:
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case "O":
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continue
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case "#":
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crashed = True
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break
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case _:
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crashed = False
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break
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if crashed:
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continue
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grid[y + dist * dy, x + dist * dx] = "O"
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case _:
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pass
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grid[y, x] = "."
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x += dx
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y += dy
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grid[y, x] = "@"
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stones = numpy.where(grid == "O")
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return sum(100 * y + x for y, x in zip(*stones))
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@classmethod
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def part2(cls, input: str) -> None:
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input = input.replace(".", "..")
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input = input.replace("#", "##")
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input = input.replace("O", "[]")
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input = input.replace("@", "@.")
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grid, steps = parse_input(input)
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y, x = numpy.where(grid == "@")
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x, y = x[0], y[0]
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for c in steps:
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dx, dy = convert_dir(c)
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match grid[y + dy, x + dx]:
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case "#":
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continue
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case "]" | "[":
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crashed = False
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if dy == 0:
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# easy case: just move linearly
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for dist in itertools.count(2):
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match grid[y, x + dist * dx]:
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case "[" | "]":
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continue
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case "#":
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crashed = True
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break
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case _:
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break
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if crashed:
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continue
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# shuffle all grid points one over
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for steps in range(dist, 1, -1):
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grid[y, x + dx * steps] = grid[y, x + dx * (steps - 1)]
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else:
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if grid[y + dy, x] == "[":
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to_check = {x, x + 1}
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else:
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to_check = {x, x - 1}
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moving_stones = [to_check]
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for dist in itertools.count(2):
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to_check_next = set()
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for cx in to_check:
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match grid[y + dist * dy, cx]:
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case "#":
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crashed = True
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break
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case "[":
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to_check_next.add(cx)
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to_check_next.add(cx + 1)
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case "]":
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to_check_next.add(cx)
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to_check_next.add(cx - 1)
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case _:
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continue
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if crashed or not to_check_next:
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break
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moving_stones.append(to_check_next)
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to_check = to_check_next
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if crashed:
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continue
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for steps in range(len(moving_stones), 0, -1):
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dist = steps + 1
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for cx in moving_stones[steps - 1]:
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grid[y + dy * dist, cx] = grid[y + dy * (dist - 1), cx]
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grid[y + dy * (dist - 1), cx] = "."
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case _:
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pass
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grid[y, x] = "."
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x += dx
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y += dy
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grid[y, x] = "@"
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stones = numpy.where(grid == "[")
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return sum(100 * y + x for y, x in zip(*stones))
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