2023 day 10

Author: sanderploegsma

2023/python/aoc_2023/day10.py

@@ -0,0 +1,50 @@
+"""Advent of Code 2023 - Day 10."""
+
+from itertools import pairwise
+from aoc_2023.input import Input
+
+UP = (0, -1)
+DOWN = (0, 1)
+LEFT = (-1, 0)
+RIGHT = (1, 0)
+
+start_directions = {
+    UP: "|F7",
+    DOWN: "|JL",
+    RIGHT: "-J7",
+    LEFT: "-FL",
+}
+
+directions = {
+    "-": {LEFT: LEFT, RIGHT: RIGHT},
+    "|": {UP: UP, DOWN: DOWN},
+    "L": {LEFT: UP, DOWN: RIGHT},
+    "J": {RIGHT: UP, DOWN: LEFT},
+    "7": {RIGHT: DOWN, UP: LEFT},
+    "F": {UP: RIGHT, LEFT: DOWN},
+}
+
+
+def move(a: tuple[int, int], b: tuple[int, int]) -> tuple[int, int]:
+    ax, ay = a
+    bx, by = b
+    return ax + bx, ay + by
+
+
+grid = Input("10.txt").grid
+start = next(coord for coord, cell in grid.items() if cell == "S")
+direction = next(d for d, s in start_directions.items() if grid.get(move(start, d), "?") in s)
+
+position = move(start, direction)
+loop = [start]
+while position != start:
+    loop.append(position)
+    symbol = grid[position]
+    direction = directions[symbol][direction]
+    position = move(position, direction)
+
+print("Part one:", len(loop) // 2)
+
+area = abs(sum(x1 * y2 - x2 * y1 for (x1, y1), (x2, y2) in pairwise([*loop, start]))) // 2
+
+print("Part two:", area - len(loop) // 2 + 1)

2023/python/aoc_2023/input.py

@@ -13,8 +13,17 @@ def text(self) -> str:
 
     @functools.cached_property
     def lines(self) -> list[str]:
-        return [line.rstrip() for line in self._text.splitlines()]
+        return list(line.rstrip() for line in self.text.splitlines())
 
     @functools.cached_property
     def ints(self) -> list[int]:
-        return [int(line.rstrip()) for line in self._text.splitlines()]
+        return list(map(int, self.lines))
+
+    @functools.cached_property
+    def grid(self) -> dict[tuple[int, int], str]:
+        result = {}
+        for y, row in enumerate(self.lines):
+            for x, cell in enumerate(row):
+                result[x, y] = cell
+
+        return result

2023/python/input/10.example-1.txt

@@ -0,0 +1,5 @@
+-L|F7
+7S-7|
+L|7||
+-L-J|
+L|-JF

2023/python/input/10.example-2.txt

@@ -0,0 +1,5 @@
+7-F7-
+.FJ|7
+SJLL7
+|F--J
+LJ.LJ

2023/python/input/10.example-3.txt

@@ -0,0 +1,9 @@
+...........
+.S-------7.
+.|F-----7|.
+.||.....||.
+.||.....||.
+.|L-7.F-J|.
+.|..|.|..|.
+.L--J.L--J.
+...........