day 22

r0f1 · r0f1 · commit 1966f131a343 · 2020-12-25T20:57:45.000+01:00
diff --git a/README.md b/README.md
@@ -23,7 +23,7 @@
 |[19](https://adventofcode.com/2020/day/19)|Monster Messages|[py](/day19/main.py), [alt](/day19/alt.py)|
 |[20](https://adventofcode.com/2020/day/20)|Jurassic Jigsaw|[py](/day20/main.py)|
 |[21](https://adventofcode.com/2020/day/21)|Allergen Assessment|[py](/day21/main.py)|
-|[22](https://adventofcode.com/2020/day/22)|-|-|
+|[22](https://adventofcode.com/2020/day/22)|Crab Combat|[py](/day22/main.py)|
 |[23](https://adventofcode.com/2020/day/23)|-|-|
 |[24](https://adventofcode.com/2020/day/24)|-|-|
 |[25](https://adventofcode.com/2020/day/25)|-|-|
diff --git a/day22/main.py b/day22/main.py
@@ -0,0 +1,57 @@
+
+with open("input.txt") as f:
+    chunks = f.read().split("\n\n")
+
+orig_p1 = list(map(int, chunks[0].strip().split("\n")[1:]))
+orig_p2 = list(map(int, chunks[1].strip().split("\n")[1:]))
+
+p1 = orig_p1.copy()
+p2 = orig_p2.copy()
+
+while len(p1) > 0 and len(p2) > 0:
+    a, b = p1.pop(0), p2.pop(0)
+    if a > b: 
+        p1 += [a,b]
+    else:
+        p2 += [b,a]
+
+if len(p1) > 0:
+    winner = p1
+else:
+    winner = p2
+
+print(sum(e*(len(winner)-i) for i, e in enumerate(winner)))
+
+# Part 2
+def play_game(p1, p2):
+    seen1, seen2 = set(), set()
+
+    while len(p1) > 0 and len(p2) > 0:
+        s1 = ",".join([str(c) for c in p1])
+        s2 = ",".join([str(c) for c in p2])
+        if s1 in seen1 or s2 in seen2:
+            return "p1", p1
+        seen1.add(s1)
+        seen2.add(s2)
+
+        a, b = p1.pop(0), p2.pop(0)
+        if a <= len(p1) and b <= len(p2):
+            winner, _ = play_game(p1.copy()[:a], p2.copy()[:b])
+        else:
+            if a > b:
+                winner = "p1"
+            else:
+                winner = "p2"
+        
+        if winner == "p1":
+            p1 += [a,b]
+        else:
+            p2 += [b,a]
+
+    if len(p1) > 0:
+        return "p1", p1
+    else:
+        return "p2", p2
+    
+_, w = play_game(orig_p1.copy(), orig_p2.copy())
+print(sum(e*(len(w)-i) for i, e in enumerate(w)))
