Solve 2025 day 4 pt 1-2

Had a bug in my aoc lib, that lost me an hour for pt 1:
The ADJ dict has SW twice, and lacks NE.

The bug is at least 2 years old. It was introduced in 661f18dca4
and apparently has never worked. I guess it has not been used
up until now.

That being said, it was straight-forward. A new helper for
grid was used the first time, as well as an improved vdbg()
function.

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