Solve day 4

04/card.py

@@ -0,0 +1,35 @@
+from __future__ import annotations
+
+from dataclasses import dataclass
+from functools import cached_property
+
+
+@dataclass
+class Card:
+    winning_numbers: set[int]
+    your_numbers: set[int]
+
+    @classmethod
+    def parse(cls, desc: str) -> Card:
+        try:
+            _, numbers_segment = desc.split(":")
+            winning_numbers_segment, your_numbers_segment = numbers_segment.split("|")
+            winning_numbers = {
+                int(n) for n in winning_numbers_segment.strip().split(" ") if n != ""
+            }
+            your_numbers = {
+                int(n) for n in your_numbers_segment.strip().split(" ") if n != ""
+            }
+        except:
+            raise ValueError("Card description is invalid.")
+
+        return Card(winning_numbers, your_numbers)
+
+    @cached_property
+    def match_count(self):
+        matching_numbers = self.winning_numbers.intersection(self.your_numbers)
+        return len(matching_numbers)
+
+    @cached_property
+    def points(self):
+        return 2 ** (self.match_count - 1) if self.match_count > 0 else 0