perf: optimize solution 2025/09

src/solution/year_2025/day_09.py

@@ -1,4 +1,3 @@
-from collections.abc import Generator
 from typing import Any
 
 Point = tuple[int, int]
@@ -14,10 +13,7 @@ def _parse_input(input_data) -> list[Point]:
 
 
 def _rectangle_size(p1: Point, p2: Point) -> int:
-    x1, y1 = p1
-    x2, y2 = p2
-
-    return (abs(x1 - x2) + 1) * (abs(y1 - y2) + 1)
+    return (abs(p1[0] - p2[0]) + 1) * (abs(p1[1] - p2[1]) + 1)
 
 
 def part_1(input_data: str) -> Any:
@@ -47,22 +43,8 @@ def _get_dir(p1: Point, p2: Point) -> Point:
     return dx, dy
 
 
-def _get_segment(p1: Point, p2: Point) -> Generator[Point]:
-    dx, dy = _get_dir(p1, p2)
-
-    points = []
-
-    sx, sy = p1
-    while (sx, sy) != p2:
-        yield sx, sy
-        points.append((sx, sy))
-        sx, sy = sx + dx, sy + dy
-
-    yield p2
-
-
 def _compress_coordinates(points: list[Point], y: bool) -> dict[int, int]:
-    return {v: k for k, v in enumerate(sorted({p[y] for p in points}))}
+    return {v: k for k, v in enumerate(sorted({p[y] for p in points}), 1)}
 
 
 def _find_inner(
@@ -80,15 +62,17 @@ def _find_inner(
 
         c1, c2 = c(p1), c(p2)
 
-        rng = _get_segment(c1, c2)
-
+        x, y = c1
         dx, dy = _get_dir(c1, c2)
-        # rotate 90 positive as inside is in the positive direction
-        dx, dy = -dy, dx
+        pdx, pdy = -dy, dx
 
-        for x, y in rng:
+        while (x, y) != c2:
             inner.add((x, y))
-            inside.add((x + dx, y + dy))
+            inside.add((x + pdx, y + pdy))
+            x, y = x + dx, y + dy
+
+        inner.add((x, y))
+        inside.add((x + pdx, y + pdy))
 
     stack = list(inside - inner)
 
@@ -106,18 +90,6 @@ def _find_inner(
     return inner
 
 
-def _get_corner_points(p1: Point, p2: Point) -> tuple[Point, ...]:
-    if p1 == p2:
-        return (p1,)
-
-    px1, py1 = p1
-    px2, py2 = p2
-    p3 = px1, py2
-    p4 = px2, py1
-
-    return p1, p3, p2, p4
-
-
 def part_2(input_data: str) -> Any:
     points = _parse_input(input_data)
 
@@ -129,6 +101,19 @@ def part_2(input_data: str) -> Any:
 
     inner = _find_inner(points, x_compression, y_compression)
 
+    w = max(x_compression.values())
+    h = max(y_compression.values())
+
+    prefix = [[0] * (h + 1) for _ in range(w + 1)]
+    for x in range(1, w + 1):
+        for y in range(1, h + 1):
+            prefix[x][y] = (
+                ((x, y) in inner)
+                + prefix[x - 1][y]
+                + prefix[x][y - 1]
+                - prefix[x - 1][y - 1]
+            )
+
     m = None
 
     for idx, p1 in enumerate(points):
@@ -136,19 +121,28 @@ def part_2(input_data: str) -> Any:
         for p2 in points[idx + 1 :]:
             c2 = c(p2)
 
-            c1, c2, c3, c4 = _get_corner_points(c1, c2)
+            size = _rectangle_size(p1, p2)
+            if m and size <= m:
+                continue
 
-            is_inside = (
-                all(x in inner for x in _get_segment(c1, c2))
-                and all(x in inner for x in _get_segment(c2, c3))
-                and all(x in inner for x in _get_segment(c3, c4))
-                and all(x in inner for x in _get_segment(c4, c1))
+            min_x = min(c1[0], c2[0])
+            max_x = max(c1[0], c2[0])
+            min_y = min(c1[1], c2[1])
+            max_y = max(c1[1], c2[1])
+
+            c_expected_size = _rectangle_size(c1, c2)
+            c_size = (
+                prefix[max_x][max_y]
+                - prefix[min_x - 1][max_y]
+                - prefix[max_x][min_y - 1]
+                + prefix[min_x - 1][min_y - 1]
             )
 
+            is_inside = c_size == c_expected_size
+
             if not is_inside:
                 continue
 
-            size = _rectangle_size(p1, p2)
             m = max(m or size, size)
 
     return m