2017 Day 11 Part 1

2017/.gitignore

@@ -0,0 +1 @@
+input

2017/aoc.py

@@ -0,0 +1,10 @@
+import os
+
+
+def input_path(day: int) -> str:
+    return os.path.join(os.path.dirname(__file__), "input", f"day{day:>02}")
+
+
+def puzzle_input(day: int) -> str:
+    with open(input_path(day)) as f:
+        return f.read().strip()

2017/day11.py

@@ -0,0 +1,59 @@
+from enum import Enum
+from typing import Tuple, Iterable
+
+import aoc
+
+HexPos = Tuple[int, int, int]
+
+
+class Direction(Enum):
+    N = 0
+    NE = 1
+    SE = 2
+    S = 3
+    SW = 4
+    NW = 5
+
+    @classmethod
+    def parse(cls, s: str):
+        match s:
+            case 'n': return Direction.N
+            case 's': return Direction.S
+            case 'ne': return Direction.NE
+            case 'nw': return Direction.NW
+            case 'se': return Direction.SE
+            case 'sw': return Direction.SW
+            case _: raise ValueError(f"unknown direction: {s}")
+
+
+def part1():
+    steps = map(Direction.parse, aoc.puzzle_input(11).split(","))
+    return distance(walk(steps))
+
+
+def walk(steps: Iterable[Direction]) -> HexPos:
+    pos = (0, 0, 0)
+    for step in steps:
+        pos = move(pos, step)
+    return pos
+
+
+def distance(pos: HexPos) -> int:
+    assert sum(pos) == 0, pos
+    return sum(map(abs, pos)) // 2
+
+
+def move(pos: HexPos, dir: Direction) -> HexPos:
+    (q, r, s) = pos
+    match dir:
+        case Direction.N: return (q, r-1, s+1)
+        case Direction.S: return (q, r+1, s-1)
+
+        case Direction.NE: return (q+1, r-1, s)
+        case Direction.SW: return (q-1, r+1, s)
+
+        case Direction.NW: return (q-1, r, s+1)
+        case Direction.SE: return (q+1, r, s-1)
+
+
+print(part1())