day 4 part 2 (in Python)

solve.py

@@ -1,22 +1,31 @@
 #!/usr/bin/env python3
 import sys
+from dataclasses import dataclass
+
+@dataclass
+class Row:
+    cards: int
+    matches: int
 
 sum = 0
+rows = []
 for line in sys.stdin:
     _, nums = line.split(":")
     winning, mine = nums.split("|")
 
     winning = set(winning.split())
-    if len(winning) != len(set(winning)):
-        raise ValueError("Shenannigans!")
-
     mine = set(mine.split())
-    if len(mine) != len(set(mine)):
-        raise ValueError("Shenannigans! {}".format(mine))
 
     both = winning.intersection(mine)
-    c = len(both)
-    if c > 0:
-        sum += 2 ** (c - 1)
+    rows.append(Row(matches=len(both), cards=1))
+
+for i in range(len(rows)):
+    m = rows[i]
+    for j in range(m.matches):
+        rows[i + 1 + j].cards += m.cards
+
+for row in rows:
+    sum += row.cards
+    print(row)
 
 print(sum)