Implement 2024 day 12

2024/src/aoc/days/day12.py

@@ -0,0 +1,101 @@
+import numpy
+
+from . import CombinedRunner
+
+DIRECTIONS = [
+    (-1, 0),
+    (1, 0),
+    (0, -1),
+    (0, 1),
+]
+
+
+class DayRunner(CombinedRunner):
+    @classmethod
+    def run_both(cls, input: str) -> tuple[int, int]:
+        grid = numpy.array(list(map(list, input.strip().split("\n"))))
+
+        score = 0
+        score2 = 0
+
+        for y in range(grid.shape[0]):
+            for x in range(grid.shape[1]):
+                if grid[y, x] == ".":
+                    continue
+
+                search = grid[y, x]
+                grid[y, x] = "."
+
+                todo = [(y, x)]
+                cluster = {(y, x)}
+
+                def enqueue(y, x):
+                    if grid[y, x] == search:
+                        grid[y, x] = "."
+                        todo.append((y, x))
+                        cluster.add((y, x))
+
+                while todo:
+                    cy, cx = todo.pop()
+
+                    if cx > 0:
+                        enqueue(cy, cx - 1)
+                    if cy > 0:
+                        enqueue(cy - 1, cx)
+
+                    if cx < grid.shape[1] - 1:
+                        enqueue(cy, cx + 1)
+                    if cy < grid.shape[0] - 1:
+                        enqueue(cy + 1, cx)
+
+                side_length = sum(
+                    sum((cy + dy, cx + dx) not in cluster for dy, dx in DIRECTIONS)
+                    for cy, cx in cluster
+                )
+
+                corners = 0
+
+                for cy, cx in cluster:
+                    # Outer corners
+                    corners += (cy, cx - 1) not in cluster and (
+                        cy - 1,
+                        cx,
+                    ) not in cluster
+                    corners += (cy, cx + 1) not in cluster and (
+                        cy - 1,
+                        cx,
+                    ) not in cluster
+                    corners += (cy, cx - 1) not in cluster and (
+                        cy + 1,
+                        cx,
+                    ) not in cluster
+                    corners += (cy, cx + 1) not in cluster and (
+                        cy + 1,
+                        cx,
+                    ) not in cluster
+                    # Inner corners
+                    corners += (
+                        (cy, cx - 1) in cluster
+                        and (cy - 1, cx) in cluster
+                        and (cy - 1, cx - 1) not in cluster
+                    )
+                    corners += (
+                        (cy, cx + 1) in cluster
+                        and (cy - 1, cx) in cluster
+                        and (cy - 1, cx + 1) not in cluster
+                    )
+                    corners += (
+                        (cy, cx - 1) in cluster
+                        and (cy + 1, cx) in cluster
+                        and (cy + 1, cx - 1) not in cluster
+                    )
+                    corners += (
+                        (cy, cx + 1) in cluster
+                        and (cy + 1, cx) in cluster
+                        and (cy + 1, cx + 1) not in cluster
+                    )
+
+                score += side_length * len(cluster)
+                score2 += corners * len(cluster)
+
+        return (score, score2)