AoC 2020: day24

Signed-off-by: Ettore Dreucci <ettore.dreucci@gmail.com>

2020-python/solutions/day_24.py

@@ -0,0 +1,131 @@
+"""AOC 2020 Day 24"""
+
+import pathlib
+import time
+import re
+import operator
+import itertools
+
+TEST_INPUT = """sesenwnenenewseeswwswswwnenewsewsw
+neeenesenwnwwswnenewnwwsewnenwseswesw
+seswneswswsenwwnwse
+nwnwneseeswswnenewneswwnewseswneseene
+swweswneswnenwsewnwneneseenw
+eesenwseswswnenwswnwnwsewwnwsene
+sewnenenenesenwsewnenwwwse
+wenwwweseeeweswwwnwwe
+wsweesenenewnwwnwsenewsenwwsesesenwne
+neeswseenwwswnwswswnw
+nenwswwsewswnenenewsenwsenwnesesenew
+enewnwewneswsewnwswenweswnenwsenwsw
+sweneswneswneneenwnewenewwneswswnese
+swwesenesewenwneswnwwneseswwne
+enesenwswwswneneswsenwnewswseenwsese
+wnwnesenesenenwwnenwsewesewsesesew
+nenewswnwewswnenesenwnesewesw
+eneswnwswnwsenenwnwnwwseeswneewsenese
+neswnwewnwnwseenwseesewsenwsweewe
+wseweeenwnesenwwwswnew"""
+
+STEPMAP = {
+    'e': (1, 0),
+    'se': (1, 1),
+    'sw': (0, 1),
+    'w': (-1, 0),
+    'nw': (-1, -1),
+    'ne': (0, -1)
+}
+
+def read_input(input_path: str) -> str:
+    """take input file path and return a str with the file's content"""
+    with open(input_path, 'r') as input_file:
+        input_data = input_file.read().strip()
+        return input_data
+
+def extract(input_data: str) -> set:
+    """take input data and return the appropriate data structure"""
+    rexp_steps = re.compile(r'e|se|sw|w|nw|ne')
+    tiles_steps = [rexp_steps.findall(line) for line in input_data.split('\n')]
+
+    black_tiles = set()
+
+    for steps in tiles_steps:
+        dst_tile = find_dst_tile(steps)
+        if dst_tile in black_tiles:
+            black_tiles.remove(dst_tile)
+        else:
+            black_tiles.add(dst_tile)
+
+    return black_tiles
+
+def find_dst_tile(steps: list) -> tuple:
+    """calculate the destination tile based on the steps"""
+    x_dst, y_dst = 0, 0
+    for step in steps:
+        d_x, d_y = STEPMAP[step]
+        x_dst += d_x
+        y_dst += d_y
+
+    return x_dst, y_dst
+
+def count_black_neighbors(tiles: set, x_tile: int, y_tile: int) -> int:
+    """return the number of black adjacent tile of a given one"""
+    return sum((x_tile+d_x, y_tile+d_y) in tiles for d_x, d_y in STEPMAP.values())
+
+def calculate_floor_bounds(tiles: set) -> tuple:
+    """return the floor boundaries"""
+    min_x = min(map(operator.itemgetter(0), tiles)) - 1
+    min_y = min(map(operator.itemgetter(1), tiles)) - 1
+    max_x = max(map(operator.itemgetter(0), tiles)) + 2
+    max_y = max(map(operator.itemgetter(1), tiles)) + 2
+
+    return range(min_x, max_x), range(min_y, max_y)
+
+def flip_tiles(tiles: set) -> set:
+    """calculate the new daily floor"""
+    new_floor = set()
+
+    for tile in itertools.product(*calculate_floor_bounds(tiles)):
+        black_neighbors = count_black_neighbors(tiles, *tile)
+
+        if tile in tiles and not (black_neighbors == 0 or black_neighbors > 2):
+            new_floor.add(tile)
+        elif tile not in tiles and black_neighbors == 2:
+            new_floor.add(tile)
+
+    return new_floor
+
+def part1(entries: set) -> int:
+    """part1 solver"""
+    return len(entries)
+
+def part2(entries: list) -> int:
+    """part2 solver"""
+    for _ in range(100):
+        entries = flip_tiles(entries)
+
+    return len(entries)
+
+def test_input_day_24():
+    """pytest testing function"""
+    entries = extract(TEST_INPUT)
+    assert part1(entries) == 10
+    assert part2(entries) == 2208
+
+def test_bench_day_24(benchmark):
+    """pytest-benchmark function"""
+    benchmark(main)
+
+def main():
+    """main function"""
+    input_path = str(pathlib.Path(__file__).resolve().parent.parent) + "/inputs/" + str(pathlib.Path(__file__).stem)
+    start_time = time.time()
+    input_data = read_input(input_path)
+    entries = extract(input_data)
+    print("Part 1: %s" % part1(entries))
+    print("Part 2: %s" % part2(entries))
+    end_time = time.time()
+    print("Execution time: %f" % (end_time-start_time))
+
+if __name__ == "__main__":
+    main()