diff --git a/README.md b/README.md index 844e0e7..16607e5 100644 --- a/README.md +++ b/README.md @@ -16,4 +16,4 @@ Development occurs in language-specific directories: |[Day9.hs](hs/src/Day9.hs)|[Day9.kt](kt/aoc2024-lib/src/commonMain/kotlin/com/github/ephemient/aoc2024/Day9.kt)|[day9.py](py/aoc2024/day9.py)|[day9.rs](rs/src/day9.rs)| |[Day10.hs](hs/src/Day10.hs)|[Day10.kt](kt/aoc2024-lib/src/commonMain/kotlin/com/github/ephemient/aoc2024/Day10.kt)|[day10.py](py/aoc2024/day10.py)|[day10.rs](rs/src/day10.rs)| |[Day11.hs](hs/src/Day11.hs)|[Day11.kt](kt/aoc2024-lib/src/commonMain/kotlin/com/github/ephemient/aoc2024/Day11.kt)|[day11.py](py/aoc2024/day11.py)|[day11.rs](rs/src/day11.rs)| -|[Day12.hs](hs/src/Day12.hs)|[Day12.kt](kt/aoc2024-lib/src/commonMain/kotlin/com/github/ephemient/aoc2024/Day12.kt)||| +|[Day12.hs](hs/src/Day12.hs)|[Day12.kt](kt/aoc2024-lib/src/commonMain/kotlin/com/github/ephemient/aoc2024/Day12.kt)|[day12.py](py/aoc2024/day12.py)|| diff --git a/py/aoc2024/day12.py b/py/aoc2024/day12.py new file mode 100644 index 0000000..6ea3a6f --- /dev/null +++ b/py/aoc2024/day12.py @@ -0,0 +1,146 @@ +""" +Day 12: Garden Groups +""" + +from collections import Counter, defaultdict +import textwrap +from typing import Generator + +SAMPLE_INPUT_1 = textwrap.dedent( + """\ + AAAA + BBCD + BBCC + EEEC + """ +) +SAMPLE_INPUT_2 = textwrap.dedent( + """\ + OOOOO + OXOXO + OOOOO + OXOXO + OOOOO + """ +) +SAMPLE_INPUT_3 = textwrap.dedent( + """\ + RRRRIICCFF + RRRRIICCCF + VVRRRCCFFF + VVRCCCJFFF + VVVVCJJCFE + VVIVCCJJEE + VVIIICJJEE + MIIIIIJJEE + MIIISIJEEE + MMMISSJEEE + """ +) +SAMPLE_INPUT_4 = textwrap.dedent( + """\ + EEEEE + EXXXX + EEEEE + EXXXX + EEEEE + """ +) +SAMPLE_INPUT_5 = textwrap.dedent( + """\ + AAAAAA + AAABBA + AAABBA + ABBAAA + ABBAAA + AAAAAA + """ +) + + +def _groups(data: str) -> Generator[set[tuple[int, int]]]: + lines = data.splitlines() + visited = set() + for y, line in enumerate(lines): + for x, char in enumerate(line): + group = set() + stack = [(y, x)] + while stack: + y2, x2 = pos = stack.pop() + if lines[y2][x2] != char or pos in visited: + continue + visited.add(pos) + group.add(pos) + if 0 < y2: + stack.append((y2 - 1, x2)) + if 0 < x2: + stack.append((y2, x2 - 1)) + if x2 < len(lines[y2]) - 1: + stack.append((y2, x2 + 1)) + if y2 < len(lines) - 1: + stack.append((y2 + 1, x2)) + if group: + yield (group) + + +def _perimeter1(group: set[tuple[int, int]]) -> int: + edges = Counter() + for y, x in group: + edges.update( + ( + (2 * y - 1, 2 * x), + (2 * y, 2 * x - 1), + (2 * y, 2 * x + 1), + (2 * y + 1, 2 * x), + ) + ) + return sum(value == 1 for value in edges.values()) + + +def part1(data: str) -> int: + """ + >>> part1(SAMPLE_INPUT_1) + 140 + >>> part1(SAMPLE_INPUT_2) + 772 + >>> part1(SAMPLE_INPUT_3) + 1930 + """ + return sum(len(group) * _perimeter1(group) for group in _groups(data)) + + +def _perimeter2(group: set[tuple[int, int]]) -> int: + edges = defaultdict(set) + for y, x in group: + edges[(2 * y - 1, 2 * x)].add(0) + edges[(2 * y, 2 * x - 1)].add(1) + edges[(2 * y, 2 * x + 1)].add(3) + edges[(2 * y + 1, 2 * x)].add(2) + lines = defaultdict(set) + for (y, x), value in edges.items(): + if len(value) == 1: + value = next(iter(value)) + lines[x if value % 2 else y + 1].add((x + y, value)) + return sum( + 1 + sum(abs(q - p) > 2 or b != d for (q, b), (p, d) in zip(line, line[1:])) + for line in map(sorted, lines.values()) + ) + + +def part2(data: str) -> int: + """ + >>> part2(SAMPLE_INPUT_1) + 80 + >>> part2(SAMPLE_INPUT_2) + 436 + >>> part2(SAMPLE_INPUT_4) + 236 + >>> part2(SAMPLE_INPUT_5) + 368 + >>> part2(SAMPLE_INPUT_3) + 1206 + """ + return sum(len(group) * _perimeter2(group) for group in _groups(data)) + + +parts = (part1, part2) diff --git a/py/pyproject.toml b/py/pyproject.toml index 7bfffa4..f8bc0e6 100644 --- a/py/pyproject.toml +++ b/py/pyproject.toml @@ -35,6 +35,7 @@ day8 = "aoc2024.day8:parts" day9 = "aoc2024.day9:parts" day10 = "aoc2024.day10:parts" day11 = "aoc2024.day11:parts" +day12 = "aoc2024.day12:parts" [build-system] requires = ["poetry-core"]