Clean day 12.
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38b1d86514
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@ -82,6 +82,33 @@ def print_path(path: list[tuple[int, int]], n_rows: int, n_cols: int) -> None:
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print("\n".join("".join(row) for row in graph))
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print("\n".join("".join(row) for row in graph))
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def neighbors(
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grid: list[list[int]], node: tuple[int, int], up: bool
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) -> Iterator[tuple[int, int]]:
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n_rows = len(grid)
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n_cols = len(grid[0])
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c_row, c_col = node
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for n_row, n_col in (
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(c_row - 1, c_col),
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(c_row + 1, c_col),
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(c_row, c_col - 1),
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(c_row, c_col + 1),
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):
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if not (n_row >= 0 and n_row < n_rows and n_col >= 0 and n_col < n_cols):
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continue
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if up and grid[n_row][n_col] > grid[c_row][c_col] + 1:
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continue
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elif not up and grid[n_row][n_col] < grid[c_row][c_col] - 1:
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continue
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yield n_row, n_col
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# === main code ===
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lines = sys.stdin.read().splitlines()
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lines = sys.stdin.read().splitlines()
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grid = [[ord(cell) - ord("a") for cell in line] for line in lines]
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grid = [[ord(cell) - ord("a") for cell in line] for line in lines]
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@ -106,47 +133,19 @@ for i_row, row in enumerate(grid):
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grid[start[0]][start[1]] = 0
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grid[start[0]][start[1]] = 0
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grid[end[0]][end[1]] = ord("z") - ord("a")
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grid[end[0]][end[1]] = ord("z") - ord("a")
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n_rows = len(grid)
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n_cols = len(grid[0])
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def heuristic(lhs: tuple[int, int], rhs: tuple[int, int]) -> float:
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return abs(lhs[0] - rhs[0]) + abs(lhs[1] - rhs[1])
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def neighbors(node: tuple[int, int], up: bool) -> Iterator[tuple[int, int]]:
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c_row, c_col = node
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for n_row, n_col in (
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(c_row - 1, c_col),
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(c_row + 1, c_col),
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(c_row, c_col - 1),
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(c_row, c_col + 1),
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):
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if not (n_row >= 0 and n_row < n_rows and n_col >= 0 and n_col < n_cols):
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continue
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if up and grid[n_row][n_col] > grid[c_row][c_col] + 1:
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continue
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elif not up and grid[n_row][n_col] < grid[c_row][c_col] - 1:
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continue
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yield n_row, n_col
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lengths_1, parents_1 = dijkstra(
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lengths_1, parents_1 = dijkstra(
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start=start, neighbors=lambda n: neighbors(n, True), cost=lambda lhs, rhs: 1
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start=start, neighbors=lambda n: neighbors(grid, n, True), cost=lambda lhs, rhs: 1
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)
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)
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path_1 = make_path(parents_1, start, end)
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path_1 = make_path(parents_1, start, end)
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assert path_1 is not None
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assert path_1 is not None
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print_path(path_1, n_rows=len(grid), n_cols=len(grid[0]))
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print_path(path_1, n_rows=len(grid), n_cols=len(grid[0]))
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answer_1 = lengths_1[end] - 1
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print(f"answer 1 is {lengths_1[end] - 1}")
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print(f"answer 1 is {answer_1}")
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lengths_2, parents_2 = dijkstra(
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lengths_2, parents_2 = dijkstra(
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start=end, neighbors=lambda n: neighbors(n, False), cost=lambda lhs, rhs: 1
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start=end, neighbors=lambda n: neighbors(grid, n, False), cost=lambda lhs, rhs: 1
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)
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)
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answer_2 = min(lengths_2.get(start, float("inf")) for start in start_s)
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answer_2 = min(lengths_2.get(start, float("inf")) for start in start_s)
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print(f"answer 2 is {answer_2}")
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print(f"answer 2 is {answer_2}")
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