Add utilities for 2D navigation

Author: sanderploegsma

2023/python/aoc_2023/day10.py

@@ -1,12 +1,9 @@
 """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)
+from aoc_2023.input import Input
+from aoc_2023.navigation import UP, DOWN, LEFT, RIGHT
 
 start_directions = {
     UP: "|F7",
@@ -24,24 +21,17 @@
     "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)
+direction = next(d for d, s in start_directions.items() if grid.get(start + d, "?") in s)
 
-position = move(start, direction)
+position = start + direction
 loop = [start]
 while position != start:
     loop.append(position)
     symbol = grid[position]
     direction = directions[symbol][direction]
-    position = move(position, direction)
+    position = position + direction
 
 print("Part one:", len(loop) // 2)
 

2023/python/aoc_2023/day11.py

@@ -1,10 +1,11 @@
 """Advent of Code 2023 - Day 11."""
 
-from operator import itemgetter
 from itertools import combinations
+from operator import itemgetter
 from typing import Generator
 
 from aoc_2023.input import Input
+from aoc_2023.navigation import XY, manhattan_distance
 
 
 def expand(rows: list[str], n: int) -> list[list[tuple[int, int, str]]]:
@@ -23,24 +24,17 @@ def expand(rows: list[str], n: int) -> list[list[tuple[int, int, str]]]:
     return result
 
 
-def parse(grid: list[list[tuple[int, int, str]]]) -> Generator[tuple[int, int], None, None]:
+def parse(grid: list[list[tuple[int, int, str]]]) -> Generator[XY, None, None]:
     y = 0
     for row in grid:
         x = 0
         for w, h, c in row:
             if c == "#":
-                yield x, y
+                yield XY(x, y)
             x += w
         y += row[0][1]
 
 
-def manhattan_distance(p1: tuple[int, int], p2: tuple[int, int]) -> int:
-    x1, y1 = p1
-    x2, y2 = p2
-
-    return abs(x2 - x1) + abs(y2 - y1)
-
-
 coordinates = list(parse(expand(Input("11.txt").lines, 2)))
 distances = list((p1, p2, manhattan_distance(p1, p2)) for p1, p2 in combinations(coordinates, 2))
 print("Part one:", sum(map(itemgetter(2), distances)))

2023/python/aoc_2023/input.py

@@ -1,6 +1,8 @@
 import functools
 import os
 
+from aoc_2023.navigation import XY
+
 
 class Input:
     def __init__(self, name: str):
@@ -20,10 +22,10 @@ def ints(self) -> list[int]:
         return list(map(int, self.lines))
 
     @functools.cached_property
-    def grid(self) -> dict[tuple[int, int], str]:
+    def grid(self) -> dict[XY, str]:
         result = {}
         for y, row in enumerate(self.lines):
             for x, cell in enumerate(row):
-                result[x, y] = cell
+                result[XY(x, y)] = cell
 
         return result

2023/python/aoc_2023/navigation.py

@@ -0,0 +1,32 @@
+from dataclasses import dataclass
+from typing import Iterator
+
+
+@dataclass(frozen=True)
+class XY:
+    """Represents a point on a 2-dimensional grid."""
+
+    x: int
+    y: int
+
+    def __add__(self, other):
+        return XY(self.x + other.x, self.y + other.y)
+
+    def __sub__(self, other):
+        return XY(self.x - other.x, self.y - other.y)
+
+    def __iter__(self) -> Iterator[int]:
+        yield from [self.x, self.y]
+
+
+UP = XY(0, -1)
+DOWN = XY(0, 1)
+LEFT = XY(-1, 0)
+RIGHT = XY(1, 0)
+
+
+def manhattan_distance(p1: XY, p2: XY) -> int:
+    """
+    Calculates the manhattan distance between two points on a 2-dimensional grid.
+    """
+    return abs(p2.x - p1.x) + abs(p2.y - p1.y)