2018: d09: ex2: add solution

2018/d09/ex2/ex2.py

@@ -0,0 +1,39 @@
+#!/usr/bin/env python
+
+import collections
+import sys
+
+
+def solve(input: str) -> int:
+    def parse(input: str) -> tuple[int, int]:
+        split = input.split()
+        return int(split[0]), int(split[6])
+
+    def play_game(players: int, last_marble: int) -> list[int]:
+        circle = collections.deque([0])
+        scores = [0] * players
+
+        for marble in range(1, last_marble + 1):
+            if marble % 23 == 0:
+                scores[marble % players] += marble
+                circle.rotate(7)
+                scores[marble % players] += circle.pop()
+                circle.rotate(-1)
+            else:
+                circle.rotate(-1)
+                circle.append(marble)
+
+        return scores
+
+    players, last_marble = parse(input)
+    scores = play_game(players, last_marble * 100)
+    return max(scores)
+
+
+def main() -> None:
+    input = sys.stdin.read()
+    print(solve(input))
+
+
+if __name__ == "__main__":
+    main()