Merge pull request #107 from ephemient/py/day14

Day 14: Restroom Redoubt

README.md

@@ -18,7 +18,7 @@ Development occurs in language-specific directories:
 |[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.py](py/aoc2024/day12.py)|[day12.rs](rs/src/day12.rs)|
 |[Day13.hs](hs/src/Day13.hs)|[Day13.kt](kt/aoc2024-lib/src/commonMain/kotlin/com/github/ephemient/aoc2024/Day13.kt)|[day13.py](py/aoc2024/day13.py)|[day13.rs](rs/src/day13.rs)|
-|[Day14.hs](hs/src/Day14.hs)|[Day14.kt](kt/aoc2024-lib/src/commonMain/kotlin/com/github/ephemient/aoc2024/Day14.kt)|||
+|[Day14.hs](hs/src/Day14.hs)|[Day14.kt](kt/aoc2024-lib/src/commonMain/kotlin/com/github/ephemient/aoc2024/Day14.kt)|[day14.py](py/aoc2024/day14.py)||
 |[Day15.hs](hs/src/Day15.hs)||||
 |[Day16.hs](hs/src/Day16.hs)||||
 |[Day17.hs](hs/src/Day17.hs)||||

py/aoc2024/day13.py

@@ -25,9 +25,11 @@
 
 _pattern = re.compile(r"\d+")
 
+
 def _parse(data: str) -> Generator[tuple[int, int, int, int, int, int]]:
     return zip(*((int(match.group(0)) for match in _pattern.finditer(data)),) * 6)
 
+
 def _solve(ax: int, ay: int, bx: int, by: int, x: int, y: int) -> int:
     anumerator = x * by - y * bx
     adenominator = ax * by - bx * ay
@@ -39,14 +41,20 @@ def _solve(ax: int, ay: int, bx: int, by: int, x: int, y: int) -> int:
     b = bnumerator // bdenominator
     return 3 * a + b
 
+
 def part1(data: str) -> int:
     """
     >>> part1(SAMPLE_INPUT)
     480
     """
     return sum(_solve(ax, ay, bx, by, x, y) for ax, ay, bx, by, x, y in _parse(data))
 
+
 def part2(data: str) -> int:
-    return sum(_solve(ax, ay, bx, by, x + 10000000000000, y + 10000000000000) for ax, ay, bx, by, x, y in _parse(data))
+    return sum(
+        _solve(ax, ay, bx, by, x + 10000000000000, y + 10000000000000)
+        for ax, ay, bx, by, x, y in _parse(data)
+    )
+
 
 parts = (part1, part2)

py/aoc2024/day14.py

@@ -0,0 +1,84 @@
+"""
+Day 14: Restroom Redoubt
+"""
+
+from collections import namedtuple
+from functools import partial
+from itertools import zip_longest
+from math import lcm
+from typing import Generator
+
+SAMPLE_INPUT = """
+p=0,4 v=3,-3
+p=6,3 v=-1,-3
+p=10,3 v=-1,2
+p=2,0 v=2,-1
+p=0,0 v=1,3
+p=3,0 v=-2,-2
+p=7,6 v=-1,-3
+p=3,0 v=-1,-2
+p=9,3 v=2,3
+p=7,3 v=-1,2
+p=2,4 v=2,-3
+p=9,5 v=-3,-3
+"""
+
+WIDTH, HEIGHT = 101, 103
+
+
+class _Robot(namedtuple("Robot", ("x0", "y0", "vx", "vy"))):
+    def __getitem__(
+        self, t: int, width: int = WIDTH, height: int = HEIGHT
+    ) -> tuple[int, int]:
+        return (self.x0 + t * self.vx) % width, (self.y0 + t * self.vy) % height
+
+
+def _parse(data: str) -> Generator[_Robot]:
+    for line in filter(None, data.splitlines()):
+        p, v = line.split(maxsplit=1)
+        p = p[p.index("=") + 1 :]
+        v = v[v.index("=") + 1 :]
+        yield _Robot(
+            int(p[: p.index(",")]),
+            int(p[p.index(",") + 1 :]),
+            int(v[: v.index(",")]),
+            int(v[v.index(",") + 1 :]),
+        )
+
+
+def part1(data: str, width: int = WIDTH, height: int = HEIGHT) -> int:
+    """
+    >>> part1(SAMPLE_INPUT, width=11, height=7)
+    12
+    """
+    midpoint_x, midpoint_y = width // 2, height // 2
+    q1, q2, q3, q4 = 0, 0, 0, 0
+    for robot in _parse(data):
+        x, y = robot.__getitem__(100, width=width, height=height)
+        if x > midpoint_x and y > midpoint_y:
+            q1 += 1
+        if x < midpoint_x and y > midpoint_y:
+            q2 += 1
+        if x > midpoint_x and y < midpoint_y:
+            q3 += 1
+        if x < midpoint_x and y < midpoint_y:
+            q4 += 1
+    return q1 * q2 * q3 * q4
+
+
+def _part2_key(robots: tuple[_Robot], t: int) -> int:
+    positions = sorted((robot[t] for robot in robots))
+    line, max_line = 1, 0
+    for (x, y), next in zip_longest(positions, positions[1:]):
+        if (x, y + 1) == next:
+            line += 1
+        else:
+            line, max_line = 1, max(line, max_line)
+    return -max_line, t
+
+
+def part2(data: str) -> int:
+    return min(range(lcm(WIDTH * HEIGHT)), key=partial(_part2_key, tuple(_parse(data))))
+
+
+parts = (part1, part2)

py/pyproject.toml

@@ -37,6 +37,7 @@ day10 = "aoc2024.day10:parts"
 day11 = "aoc2024.day11:parts"
 day12 = "aoc2024.day12:parts"
 day13 = "aoc2024.day13:parts"
+day14 = "aoc2024.day14:parts"
 
 [build-system]
 requires = ["poetry-core"]