From f9fe016835ef97a31ad73db42ffa17a3a36bb722 Mon Sep 17 00:00:00 2001
From: "Peter J. Holzer" <hjp@hjp.at>
Date: Sat, 26 Dec 2020 22:07:03 +0100
Subject: [PATCH] Complete day 15, part 2

---
 15/part2 | 30 ++++++++++++++++++++++++++++++
 1 file changed, 30 insertions(+)
 create mode 100755 15/part2

diff --git a/15/part2 b/15/part2
new file mode 100755
index 0000000..65dc2a7
--- /dev/null
+++ b/15/part2
@@ -0,0 +1,30 @@
+#!/usr/bin/python3
+
+import sys
+import time
+from pprint import pprint
+
+turn = 0
+num = None
+last_turn = {}
+
+for a in sys.argv[1:]:
+    last_turn[num] = turn
+    turn += 1
+    num = int(a)
+
+pprint(last_turn)
+
+while True:
+    if num in last_turn:
+        new_num = turn - last_turn[num]
+    else:
+        new_num = 0
+    last_turn[num] = turn
+    num = new_num
+    turn += 1
+    if turn % 100000 == 0:
+        print(turn, num)
+        if turn == 30000000:
+            break
+