2022: d18: ex1: add solution

2022/d18/ex1/ex1.py

@@ -0,0 +1,43 @@
+#!/usr/bin/env python
+
+import sys
+from collections.abc import Iterator
+from typing import NamedTuple
+
+
+class Point3(NamedTuple):
+    x: int
+    y: int
+    z: int
+
+    @classmethod
+    def from_input(cls, input: str) -> "Point3":
+        x, y, z = map(int, input.split(","))
+        return cls(x, y, z)
+
+    @classmethod
+    def neighbours(cls, p: "Point3") -> Iterator["Point3"]:
+        for dx, dy, dz in (
+            (0, 0, -1),
+            (0, 0, 1),
+            (0, -1, 0),
+            (0, 1, 0),
+            (-1, 0, 0),
+            (1, 0, 0),
+        ):
+            yield cls(p.x + dx, p.y + dy, p.z + dz)
+
+
+def solve(input: list[str]) -> int:
+    cubes = {Point3.from_input(line) for line in input}
+
+    return sum(1 for p in cubes for n in Point3.neighbours(p) if n not in cubes)
+
+
+def main() -> None:
+    input = sys.stdin.read().splitlines()
+    print(solve(input))
+
+
+if __name__ == "__main__":
+    main()