day18 finished

README.md

@@ -8,6 +8,9 @@ I use python 3.11 without any libraries beyond the standard.
 
 | Day | Time      | Rank  | Score | Time     | Rank  | Score |
 | --- | --------- | ----- | ----- | -------- | ----- | ----- |
+| 18  | 00:31:49  | 3269  |    0  | 01:51:15 |  3121 |     0 |
+| 17  | 01:21:11  | 2058  |    0  | 02:42:45 |  1665 |     0 |
+| 16  | 02:44:20  | 2611  |    0  |     >24h | 10509 |     0 |
 | 15  | 00:58:10  | 3963  |    0  | 02:26:22 |  4011 |     0 |
 | 14  | 00:58:39  | 4431  |    0  | 01:18:15 |  4620 |     0 |
 | 13  | 01:23:44  | 5522  |    0  | 01:45:59 |  5610 |     0 |

advent/days/day18/data/example01.txt

@@ -0,0 +1,13 @@
+2,2,2
+1,2,2
+3,2,2
+2,1,2
+2,3,2
+2,2,1
+2,2,3
+2,2,4
+2,2,6
+1,2,5
+3,2,5
+2,1,5
+2,3,5

advent/days/day18/solution.py

@@ -0,0 +1,129 @@
+from __future__ import annotations
+from dataclasses import dataclass
+from enum import Enum
+
+from typing import Iterable, Iterator, Self
+
+day_num = 18
+
+
+def part1(lines: Iterator[str]) -> int:
+    shower = Shower.create(Position.parse_all(lines))
+    return shower.faces
+
+
+def part2(lines: Iterator[str]) -> int:
+    shower = Shower.create(Position.parse_all(lines))
+    return shower.faces - shower.count_trapped_droplets()
+
+
+@dataclass(slots=True, frozen=True)
+class Position:
+    x: int
+    y: int
+    z: int
+
+    @classmethod
+    def parse(cls, line: str) -> Self:
+        x, y, z = line.split(",")
+        return Position(int(x), int(y), int(z))
+
+    @classmethod
+    def parse_all(cls, lines: Iterable[str]) -> Iterator[Self]:
+        return (cls.parse(line) for line in lines)
+
+    def neighbors(self) -> Iterator[Position]:
+        yield Position(self.x + 1, self.y, self.z)
+        yield Position(self.x - 1, self.y, self.z)
+        yield Position(self.x, self.y + 1, self.z)
+        yield Position(self.x, self.y - 1, self.z)
+        yield Position(self.x, self.y, self.z + 1)
+        yield Position(self.x, self.y, self.z - 1)
+
+    def min_max(self, mm: tuple[Position, Position] | None) -> tuple[Position, Position]:
+        if mm is None:
+            return self, self
+
+        return (Position(min(mm[0].x, self.x),
+                         min(mm[0].y, self.y),
+                         min(mm[0].z, self.z)),
+                Position(max(mm[1].x, self.x),
+                         max(mm[1].y, self.y),
+                         max(mm[1].z, self.z)))
+
+    def is_between(self, min: Position, max: Position) -> bool:
+        return (min.x <= self.x <= max.x
+                and min.y <= self.y <= max.y
+                and min.z <= self.z <= max.z)
+
+
+class DropletType(Enum):
+    DROP = 1
+    UNKNOWN = 2
+    OUTER = 3
+
+
+@dataclass(slots=True, frozen=True)
+class Shower:
+    droplets: dict[Position, tuple[DropletType, int]]
+    faces: int
+
+    @classmethod
+    def create(cls, positions: Iterable[Position]) -> Self:
+        droplets: dict[Position, tuple[DropletType, int]] = {}
+        faces = 0
+        for position in positions:
+            candidate = droplets.get(position)
+            if candidate is not None:
+                _, touching_faces = candidate
+            else:
+                touching_faces = 0
+
+            faces += 6
+            for neighbor in position.neighbors():
+                candidate = droplets.get(neighbor)
+                if candidate is not None:
+                    droplet_type, neighbor_touching_faces = candidate
+                    if droplet_type == DropletType.DROP:
+                        touching_faces += 1
+                        faces -= 2
+                    droplets[neighbor] = droplet_type, neighbor_touching_faces + 1
+                else:
+                    droplets[neighbor] = DropletType.UNKNOWN, 1
+            droplets[position] = DropletType.DROP, touching_faces
+        return Shower(droplets, faces)
+
+    def count_trapped_droplets(self) -> int:
+        droplets = self.droplets.copy()
+        minmax: tuple[Position, Position] | None = None
+        for position in droplets.keys():
+            minmax = position.min_max(minmax)
+        if minmax is None:
+            raise Exception("I got no data to work with")
+        min_values, max_values = minmax
+
+        todo: list[Position] = [min_values]
+        while todo:
+            current = todo[0]
+            todo = todo[1:]
+
+            candidate = droplets.get(current)
+
+            skip_further = True
+            if candidate is None:
+                droplets[current] = DropletType.OUTER, 0
+                skip_further = False
+            else:
+                droplet_type, faces = candidate
+                if droplet_type == DropletType.UNKNOWN:
+                    droplets[current] = DropletType.OUTER, faces
+                    skip_further = False
+
+            if not skip_further:
+                for neighbor in current.neighbors():
+                    if neighbor.is_between(min_values, max_values):
+                        todo.append(neighbor)
+
+        return sum(touching_faces
+                   for droplet_type, touching_faces in droplets.values()
+                   if droplet_type == DropletType.UNKNOWN)

advent/days/day18/test_solution.py

@@ -0,0 +1,38 @@
+from advent.common import input
+
+from .solution import Position, Shower, day_num, part1, part2
+
+
+def test_part1():
+    lines = input.read_lines(day_num, 'example01.txt')
+    expected = 64
+    result = part1(lines)
+    assert result == expected
+
+
+def test_part2():
+    lines = input.read_lines(day_num, 'example01.txt')
+    expected = 58
+    result = part2(lines)
+    assert result == expected
+
+
+def test_simple_count():
+    lines = ["1,1,1", "1,1,2"]
+    expected = 10
+    result = Shower.create(Position.parse_all(lines))
+    assert result.faces == expected
+
+
+def test_example_faces():
+    lines = input.read_lines(day_num, 'example01.txt')
+    expected = 64
+    result = Shower.create(Position.parse_all(lines))
+    assert result.faces == expected
+
+
+def test_example_trapped():
+    lines = input.read_lines(day_num, 'example01.txt')
+    expected = 6
+    result = Shower.create(Position.parse_all(lines))
+    assert result.count_trapped_droplets() == expected

advent/days/day__/test_solution.py

@@ -4,14 +4,14 @@ from .solution import day_num, part1, part2
 
 
 def test_part1():
-    lines = input.read_lines(day_num, 'test01.txt')
+    lines = input.read_lines(day_num, 'example01.txt')
     expected = None
     result = part1(lines)
     assert result == expected
 
 
 def test_part2():
-    lines = input.read_lines(day_num, 'test01.txt')
+    lines = input.read_lines(day_num, 'example01.txt')
     expected = None
     result = part2(lines)
     assert result == expected