1 files changed, 50 insertions, 0 deletions

diff --git a/day4/__init__.py b/day4/__init__.py
new file mode 100644
index 0000000..677da75
--- /dev/null
+++ b/day4/__init__.py
@@ -0,0 +1,50 @@
+# -*- coding: utf-8 -*-
+from abc import ABC
+from typing import Iterator
+
+from aoc import BaseAssignment
+
+I = tuple[list[int], list[int]]
+T = int
+
+
+class Assignment(BaseAssignment, ABC):
+    def winning_numbers(self, winning: list[int], owned: list[int]) -> set[int]:
+        return set(winning) & set(owned)
+
+    def parse_numbers(self, numbers: str) -> list[int]:
+        return [int(num) for num in numbers.split(" ") if num != ""]
+
+    def parse_item(self, item: str) -> I:
+        _, numbers = item.split(": ")
+        winning, owned = numbers.split(" | ")
+
+        return self.parse_numbers(winning), self.parse_numbers(owned)
+
+
+class AssignmentOne(Assignment):
+    example_result = 13
+
+    def points(self, winning: list[int], owned: list[int]) -> int:
+        overlap = len(self.winning_numbers(winning, owned))
+        return overlap if overlap < 2 else 2 ** (overlap - 1)
+
+    def run(self, input: Iterator[I]) -> T:
+        return sum(self.points(winning, owned) for winning, owned in input)
+
+
+class AssignmentTwo(Assignment):
+    example_result = 30
+
+    def run(self, input: Iterator[I]) -> T:
+        cards = list(input)
+        count = {index: 1 for index, _ in enumerate(cards)}
+
+        for index, (winning, owned) in enumerate(cards):
+            for i in range(len(self.winning_numbers(winning, owned))):
+                winning_index = index + i + 1
+
+                if winning_index in count:
+                    count[winning_index] += count[index]
+
+        return sum(count.values())