2025-python/output/day_04.py

@@ -0,0 +1,31 @@
+from output import grid, ADJ
+
+
+def solve(data):
+    p1 = 0
+    p2 = set()
+    G = grid(data, o="@")
+    while True:
+        for r, c in G:
+            if sum((r + dy, c + dx) in G for dy, dx in ADJ) < 4:
+                p2.add((r, c))
+        if p1 == 0:
+            p1 = len(p2)
+        if not G & p2:
+            break
+        G = G - p2
+    p2 = len(p2)
+    return p1, p2
+
+
+if __name__ == "__main__":
+    with open("./input/04.txt", "r") as f:
+        inp = f.read().strip()
+
+    p1, p2 = solve(inp)
+
+    print(p1)
+    print(p2)
+
+    assert p1 == 1493
+    assert p2 == 9194