Day 22

2020/day22.py

@@ -0,0 +1,57 @@
+import sys
+
+def main():
+    lines = [line.rstrip() for line in sys.stdin]
+    deck1, deck2 = parse_lines(lines)
+
+    # Part 1
+    while deck1 and deck2:
+        c1, c2 = deck1.pop(0), deck2.pop(0)
+        if c1 > c2:
+            deck1 += [c1, c2]
+        else:
+            deck2 += [c2, c1]
+    deck_win = deck1 or deck2
+    print("Score:", score(deck_win))
+
+    # Part 2
+    deck1, deck2 = parse_lines(lines)
+    winner = rec_game(deck1, deck2)
+    deck_win = deck1 if winner == 1 else deck2
+    print("Score:", score(deck_win))
+
+def parse_lines(lines):
+    deck1, deck2 = [], []
+    for line in lines:
+        if not line:
+            continue
+        if line.startswith("P"):
+            deck = deck1 if int(line[7:8]) == 1 else deck2
+        else:
+            deck.append(int(line))
+    return deck1, deck2
+
+def score(deck):
+    return sum(c * (i + 1) for i, c in enumerate(reversed(deck)))
+
+def rec_game(deck1, deck2):
+    past_decks = set()
+    while deck1 and deck2:
+        h = tuple(deck1), tuple(deck2)
+        if h in past_decks:
+            return 1
+        past_decks.add(h)
+        c1, c2 = deck1.pop(0), deck2.pop(0)
+        if len(deck1) >= c1 and len(deck2) >= c2:
+            if rec_game(deck1[:c1], deck2[:c2]) == 1:
+                deck1 += [c1, c2]
+            else:
+                deck2 += [c2, c1]
+        elif c1 > c2:
+            deck1 += [c1, c2]
+        else:
+            deck2 += [c2, c1]
+    return 1 if deck1 else 2
+
+if __name__ == "__main__":
+    main()

2020/new.py

@@ -6,11 +6,9 @@ from datetime import date
 TEMPLATE = """\
 import sys
 
-
 def main():
     lines = [line.rstrip() for line in sys.stdin]
 
-
 if __name__ == "__main__":
     main()
 """