feat: solve day 20 part 1

20/main.py

@@ -0,0 +1,149 @@
+from dataclasses import dataclass
+from typing import Iterator, Optional
+from math import floor
+
+@dataclass
+class Tile:
+    top: str
+    left: str
+    right: str
+    bottom: str
+
+    def __repr__(self) -> str:
+        return "Tile"
+
+TilesData = dict[int, Tile]
+TileGrid = list[list[Optional[tuple[int, Tile]]]]
+
+def parse_tile(tile_data: str) -> tuple[int, Tile]:
+    lines = tile_data.splitlines()
+    id = int(lines[0][4:-1])
+    top_edge = lines[1]
+    right_edge = "".join(line[-1] for line in lines[1:])
+    left_edge = "".join(line[0] for line in lines[1:])
+    bottom_edge = lines[-1]
+    return id, Tile(top_edge, left_edge, right_edge, bottom_edge)
+
+def parse_input(filename: str) -> TilesData:
+    tiles = {}
+    with open(filename, "r") as f:
+        content = f.read()
+        for block in content.split("\n\n"):
+            id, tile = parse_tile(block)
+            tiles[id] = tile
+    return tiles
+
+def rotate_tile(tile) -> Tile:
+    return Tile(
+        top = tile.left[::-1],
+        right = tile.top,
+        bottom = tile.right[::-1],
+        left = tile.bottom
+    )
+
+def flip_tile(tile) -> Tile:
+    return Tile(
+        top = tile.bottom,
+        right = tile.right[::-1],
+        bottom = tile.top,
+        left = tile.left[::-1]
+    )
+
+def get_grid_size(tiles: TilesData) -> int:
+    return floor(len(tiles)**0.5)
+
+def get_rotated_tiles(tile: Tile) -> Iterator[Tile]:
+    yield tile
+    tile = rotate_tile(tile)
+    yield tile
+    tile = rotate_tile(tile)
+    yield tile
+    tile = rotate_tile(tile)
+    yield tile
+
+def get_tile_variants(tile: Tile) -> Iterator[Tile]:
+    for t in get_rotated_tiles(tile):
+        yield t
+
+    tile = flip_tile(tile)
+    for t in get_rotated_tiles(tile):
+        yield t
+
+def is_tile_possible(grid: TileGrid, x: int, y: int, tile: Tile) -> bool:
+    if x > 0:
+        other_tile = grid[y][x-1]
+        if other_tile and other_tile[1].right != tile.left:
+            return False
+
+    if x < len(grid[0])-1:
+        other_tile = grid[y][x+1]
+        if other_tile and other_tile[1].left != tile.right:
+            return False
+
+    if y > 0:
+        other_tile = grid[y-1][x]
+        if other_tile and other_tile[1].bottom != tile.top:
+            return False
+
+    if y < len(grid)-1:
+        other_tile = grid[y+1][x]
+        if other_tile and other_tile[1].top != tile.bottom:
+            return False
+
+    return True
+
+def get_possible_tiles(
+        tiles_data: TilesData,
+        used_tiles: list[int],
+        grid: TileGrid,
+        x: int,
+        y: int
+    ) -> Iterator[tuple[int, Tile]]:
+    for id in tiles_data.keys():
+        if id not in used_tiles:
+            for variant in get_tile_variants(tiles_data[id]):
+                if is_tile_possible(grid, x, y, variant):
+                    yield id, variant
+
+def solve(tiles_data: TilesData, grid: TileGrid, used_tiles: list[int]=[]) -> bool:
+    for y in range(len(grid)):
+        for x in range(len(grid[0])):
+            if grid[y][x] == None:
+                for id, tile in get_possible_tiles(tiles_data, used_tiles, grid, x, y):
+                    grid[y][x] = (id, tile)
+                    used_tiles.append(id)
+                    if solve(tiles_data, grid):
+                        return True
+                    used_tiles.pop()
+                    grid[y][x] = None
+                return False
+
+    return True
+
+def multiply_corners(grid: TileGrid) -> int:
+    w = len(grid[0])
+    h = len(grid)
+    top_left = grid[0][0]
+    top_right = grid[0][w-1]
+    bottom_left = grid[h-1][0]
+    bottom_right = grid[h-1][w-1]
+    assert top_left
+    assert top_right
+    assert bottom_left
+    assert bottom_right
+    return top_left[0] * top_right[0] * bottom_right[0] * bottom_left[0]
+
+def part1(tiles: TilesData) -> int:
+    width = get_grid_size(tiles)
+
+    grid: TileGrid = []
+    for _ in range(width):
+        grid.append([None]*width)
+
+    solve(tiles, grid)
+
+    return multiply_corners(grid)
+
+if __name__ == "__main__":
+    tiles = parse_input("input.txt")
+    print("part1: ", part1(tiles))

20/test.txt

@@ -0,0 +1,107 @@
+Tile 2311:
+..##.#..#.
+##..#.....
+#...##..#.
+####.#...#
+##.##.###.
+##...#.###
+.#.#.#..##
+..#....#..
+###...#.#.
+..###..###
+
+Tile 1951:
+#.##...##.
+#.####...#
+.....#..##
+#...######
+.##.#....#
+.###.#####
+###.##.##.
+.###....#.
+..#.#..#.#
+#...##.#..
+
+Tile 1171:
+####...##.
+#..##.#..#
+##.#..#.#.
+.###.####.
+..###.####
+.##....##.
+.#...####.
+#.##.####.
+####..#...
+.....##...
+
+Tile 1427:
+###.##.#..
+.#..#.##..
+.#.##.#..#
+#.#.#.##.#
+....#...##
+...##..##.
+...#.#####
+.#.####.#.
+..#..###.#
+..##.#..#.
+
+Tile 1489:
+##.#.#....
+..##...#..
+.##..##...
+..#...#...
+#####...#.
+#..#.#.#.#
+...#.#.#..
+##.#...##.
+..##.##.##
+###.##.#..
+
+Tile 2473:
+#....####.
+#..#.##...
+#.##..#...
+######.#.#
+.#...#.#.#
+.#########
+.###.#..#.
+########.#
+##...##.#.
+..###.#.#.
+
+Tile 2971:
+..#.#....#
+#...###...
+#.#.###...
+##.##..#..
+.#####..##
+.#..####.#
+#..#.#..#.
+..####.###
+..#.#.###.
+...#.#.#.#
+
+Tile 2729:
+...#.#.#.#
+####.#....
+..#.#.....
+....#..#.#
+.##..##.#.
+.#.####...
+####.#.#..
+##.####...
+##..#.##..
+#.##...##.
+
+Tile 3079:
+#.#.#####.
+.#..######
+..#.......
+######....
+####.#..#.
+.#...#.##.
+#.#####.##
+..#.###...
+..#.......
+..#.###...