Solve day4

day4/part2.py

@@ -0,0 +1,37 @@
+FILE = "input.txt"
+
+options = [
+    (-1, -1), (-1, 0), (0, -1), (1, 1), (1, 0), (0, 1), (-1, 1), (1, -1)
+]
+
+def main():
+    total = 0
+    grid = [list(line.strip()) for line in open(FILE)]
+    while True:
+        accessible, grid = removal_loop(grid)
+        if accessible == 0: break
+        total += accessible
+    return total
+
+def removal_loop(grid: list[list[str]]) -> tuple[int, list[list[str]]]:
+    accessible = 0
+    for i in range(len(grid)):
+        for j in range(len(grid[0])):
+            if grid[i][j] != '@': continue
+            nearby = [
+                (i + x, j + y)
+                for (x, y) in options
+                if 0 <= i+x < len(grid) and 0 <= j+y < len(grid[0])
+            ]
+            nearbyRolls = [
+                grid[x][y]
+                for (x, y) in nearby
+                if grid[x][y] == '@'
+            ]
+            if len(nearbyRolls) < 4:
+                accessible += 1
+                grid[i][j] = '.'
+    return accessible, grid
+
+if __name__ == "__main__":
+    print(main())