day 4: small performance improvement

1 files changed, 8 insertions, 5 deletions

diff --git a/4.py b/4.py
index ed2f13c..f2c3063 100644
--- a/4.py
+++ b/4.py
@@ -34,16 +34,19 @@ class Board:
         return Board([[int(n) for n in l.split()] for l in s.split('\n')])
 
 def solve(nums: list[int], boards: list[Board]) -> tuple[int, int]:
+    indices: set[int] = { i for i in range(len(boards)) }
     wins: list[int] = []
     num: int
     for num in nums:
         i: int
         board: Board
-        for i, board in enumerate(boards):
-            if board.has_bingo: continue
-            board.call(num)
-            if board.has_bingo:
-                wins.append(num * board.unmarked_sum)
+        winners: set[int] = set()
+        for i in indices:
+            boards[i].call(num)
+            if boards[i].has_bingo:
+                wins.append(num * boards[i].unmarked_sum)
+                winners.add(i)
+        indices.difference_update(winners)
     return wins[0], wins[-1]
 
 nums: str | list[int]