From 1e789404550dc5dc164ae69f2a7b0b22e4925ea8 Mon Sep 17 00:00:00 2001
From: Sebastian Seedorf <mail@sebse.de>
Date: Wed, 30 Dec 2020 10:35:08 +0100
Subject: [PATCH] Day 23

---
 day23/input.txt |  1 +
 day23/part1.py  | 19 ++++++++++++++++++
 day23/part2.py  | 52 +++++++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 72 insertions(+)
 create mode 100644 day23/input.txt
 create mode 100644 day23/part1.py
 create mode 100644 day23/part2.py

diff --git a/day23/input.txt b/day23/input.txt
new file mode 100644
index 0000000..128a58c
--- /dev/null
+++ b/day23/input.txt
@@ -0,0 +1 @@
+952316487
diff --git a/day23/part1.py b/day23/part1.py
new file mode 100644
index 0000000..d373b56
--- /dev/null
+++ b/day23/part1.py
@@ -0,0 +1,19 @@
+#!/usr/bin/env python3
+from functools import reduce
+from tqdm import tqdm
+
+num = [list(map(int, (char for char in x.strip()))) for x in open("input.txt")][0]
+
+for _ in tqdm(range(100)):
+    destination = num[0]
+    while True:
+        destination -= 1
+        if destination == 0:
+            destination = 9
+        if not destination in num[1:4]:
+            break
+    pos = num.index(destination)
+    num = num[4:pos+1] + num[1:4] + num[pos+1:] + num[0:1]
+
+pos = num.index(1)
+print(reduce(lambda a, b: 10*a+b, num[pos+1:] + num[:pos], 0))
diff --git a/day23/part2.py b/day23/part2.py
new file mode 100644
index 0000000..d23716e
--- /dev/null
+++ b/day23/part2.py
@@ -0,0 +1,52 @@
+#!/usr/bin/env python3
+from tqdm import tqdm
+
+
+class Node:
+    value = None
+    next = None
+
+    def __init__(self, value, next):
+        self.value = value
+        self.next = next
+
+
+num = [list(map(int, (char for char in x.strip()))) for x in open("input.txt")][0]
+num = num + list(range(len(num)+1, 1000000+1))
+MAX = len(num)
+
+nodes = dict()
+nodes[num[-1]] = curr = last = Node(num[-1], None)
+for n in num[-2::-1]:
+    nodes[n] = curr = Node(n, curr)
+last.next = curr
+
+for _ in tqdm(range(10000000)):
+    pickups = []
+    lp = curr
+    for j in range(3):
+        lp = lp.next
+        pickups.append(lp.value)
+    ap = lp.next
+
+    destination = curr.value
+    while True:
+        destination -= 1
+        if destination == 0:
+            destination = MAX
+        if destination not in pickups:
+            break
+    dst = nodes[destination]
+    lp.next = dst.next
+    dst.next = curr.next
+    curr.next = ap
+    curr = curr.next
+
+while curr.value != 1:
+    curr = curr.next
+curr = curr.next
+res = curr.value
+curr = curr.next
+res *= curr.value
+
+print(res)