2018: d06: ex1: add solution

2018/d06/ex1/ex1.py

@@ -0,0 +1,75 @@
+#!/usr/bin/env python
+
+import itertools
+import sys
+from collections import Counter, defaultdict
+from typing import NamedTuple
+
+
+class Point(NamedTuple):
+    x: int
+    y: int
+
+
+def solve(input: str) -> int:
+    def parse(input: list[str]) -> list[Point]:
+        return [Point(*map(int, line.split(", "))) for line in input]
+
+    def dist(lhs: Point, rhs: Point) -> int:
+        return sum(abs(a - b) for a, b in zip(lhs, rhs))
+
+    def points_distances(coords: list[Point]) -> dict[Point, Counter[Point]]:
+        top_left = Point(min(p.x for p in coords), min(p.y for p in coords))
+        bot_right = Point(max(p.x for p in coords), max(p.y for p in coords))
+
+        return {
+            p: Counter({root: dist(root, p) for root in coords})
+            for p in map(
+                Point._make,
+                itertools.product(
+                    range(top_left.x, bot_right.x + 1),
+                    range(top_left.y, bot_right.y + 1),
+                ),
+            )
+        }
+
+    def remove_areas_on_border(
+        areas: dict[Point, set[Point]],
+        top_left: Point,
+        bot_right: Point,
+    ) -> dict[Point, set[Point]]:
+        def on_border(points: set[Point]) -> bool:
+            return any(
+                p.x in (top_left.x, bot_right.x) or p.y in (top_left.y, bot_right.y)
+                for p in points
+            )
+
+        return {root: points for root, points in areas.items() if not on_border(points)}
+
+    def points_areas(coords: list[Point]) -> dict[Point, int]:
+        top_left = Point(min(p.x for p in coords), min(p.y for p in coords))
+        bot_right = Point(max(p.x for p in coords), max(p.y for p in coords))
+
+        distances = points_distances(coords)
+        areas: dict[Point, set[Point]] = defaultdict(set)
+        for p, root_distances in distances.items():
+            closest, dist = root_distances.most_common()[-1]
+            if dist == root_distances.most_common()[-2][1]:
+                continue
+            areas[closest].add(p)
+
+        areas = remove_areas_on_border(areas, top_left, bot_right)
+        return {root: len(points) for root, points in areas.items()}
+
+    coords = parse(input.splitlines())
+    areas = points_areas(coords)
+    return max(areas.values())
+
+
+def main() -> None:
+    input = sys.stdin.read()
+    print(solve(input))
+
+
+if __name__ == "__main__":
+    main()