2 files changed, 82 insertions, 0 deletions

diff --git a/day4/__init__.py b/day4/__init__.py
new file mode 100644
index 0000000..d52d0a1
--- /dev/null
+++ b/day4/__init__.py
@@ -0,0 +1,72 @@
+# -*- coding: utf-8 -*-
+from abc import ABC
+from typing import Iterator
+
+from aoc import BaseAssignment, I, T
+from aoc.datastructures import Coordinate
+
+
+class Assignment(BaseAssignment, ABC):
+    def parse_item(cls, item: str) -> Iterator[list[str]]:
+        yield [c for c in item]
+
+    @classmethod
+    def check_accessible_coordinate(
+        cls, field: list[list[str]], coordinate: Coordinate
+    ) -> bool:
+        neighbouring_roll_count = 0
+        for neighbor in coordinate.neighbours():
+            if neighbor.in_bounds(field) and field[neighbor.y][neighbor.x] == "@":
+                neighbouring_roll_count += 1
+
+        return neighbouring_roll_count < 4
+
+    @classmethod
+    def get_accessible_coordinates(
+        cls, field: list[list[str]], coordinates: list[Coordinate]
+    ) -> list[Coordinate]:
+        accessible_coordinates = []
+        for coordinate in coordinates:
+            if field[coordinate.y][coordinate.x] != "@":
+                continue
+
+            if cls.check_accessible_coordinate(field, coordinate):
+                accessible_coordinates.append(coordinate)
+
+        return accessible_coordinates
+
+
+class AssignmentOne(Assignment):
+    example_result = 13
+
+    def run(self, input: Iterator[str]) -> int:
+        field = [next(self.parse_item(i)) for i in input]
+
+        coordinates = [
+            Coordinate(x, y) for y in range(len(field)) for x in range(len(field[y]))
+        ]
+
+        return len(self.get_accessible_coordinates(field, coordinates))
+
+
+class AssignmentTwo(Assignment):
+    example_result = 43
+
+    def run(self, input: Iterator[str]) -> int:
+        field = [next(self.parse_item(i)) for i in input]
+
+        coordinates = [
+            Coordinate(x, y) for y in range(len(field)) for x in range(len(field[y]))
+        ]
+
+        rolls_removed = 0
+        while True:
+            accessible_coordinates = self.get_accessible_coordinates(field, coordinates)
+
+            if len(accessible_coordinates) == 0:
+                return rolls_removed
+
+            for coordinate in accessible_coordinates:
+                field[coordinate.y][coordinate.x] = "."
+
+            rolls_removed += len(accessible_coordinates)
diff --git a/day4/example.txt b/day4/example.txt
new file mode 100644
index 0000000..8209399
--- /dev/null
+++ b/day4/example.txt
@@ -0,0 +1,10 @@
+..@@.@@@@.
+@@@.@.@.@@
+@@@@@.@.@@
+@.@@@@..@.
+@@.@@@@.@@
+.@@@@@@@.@
+.@.@.@.@@@
+@.@@@.@@@@
+.@@@@@@@@.
+@.@.@@@.@.