Add solution for this day

2025/04/solution.py

@@ -0,0 +1,72 @@
+from aocd import get_data
+
+data = get_data(day=4, year=2025)
+table = [list(row) for row in data.split()]
+
+roll = '@'
+empty = '.'
+
+count = 0
+
+directions = [
+	(0, 1),  # east
+	(0, -1),  # west
+	(1, 0),  # north
+	(-1, 0),  # south
+	(1, 1),  # northeast
+	(1, -1),  # northwest
+	(-1, 1),  # southeast
+	(-1, -1)  # southwest
+]
+
+# pad the table with the empty character
+padded_table = table.copy()
+padded_table.insert(0, [empty] * len(table[0]))
+padded_table.append([empty] * len(table[0]))
+for i in range(len(padded_table)):
+	padded_table[i].insert(0, empty)
+	padded_table[i].append(empty)
+
+# check 8 directions, if there is fewer than four rolls, count it as a valid position and continue
+for y in range(1, len(padded_table) - 1):
+	for x in range(1, len(padded_table[0]) - 1):
+		if padded_table[y][x] == roll:
+			roll_count = 0
+			for direction in directions:
+				dx, dy = direction
+				try:
+					if padded_table[y + dy][x + dx] == roll:
+						roll_count += 1
+				except IndexError:
+					continue
+			if roll_count < 4:
+				count += 1
+print(count)
+
+# part 2
+count_two = 0
+
+def remove_rolls(count, table):
+	for y in range(1, len(table) - 1):
+		for x in range(1, len(table[0]) - 1):
+			if table[y][x] == roll:
+				roll_count = 0
+				for direction in directions:
+					dx, dy = direction
+					try:
+						if table[y + dy][x + dx] == roll:
+							roll_count += 1
+					except IndexError:
+						continue
+				if roll_count < 4:
+					count += 1
+					table[y][x] = empty
+	return count, table
+
+prev = -1
+table_two = padded_table.copy()
+while prev != count_two:
+	prev = count_two
+	count_two, table_two = remove_rolls(count_two, table_two)
+	print(count_two)
+print(count_two)