From cefcd292ce98af21659c6a04c3dc7a8db9197447 Mon Sep 17 00:00:00 2001
From: Marcin Chrzanowski <marcin.j.chrzanowski@gmail.com>
Date: Fri, 25 Dec 2020 15:32:36 +0100
Subject: Add day 15
---
15/a.rb | 25 +++++++++++++++++++++++++
15/b.rb | 25 +++++++++++++++++++++++++
15/input.txt | 1 +
3 files changed, 51 insertions(+)
create mode 100644 15/a.rb
create mode 100644 15/b.rb
create mode 100644 15/input.txt
(limited to '15')
diff --git a/15/a.rb b/15/a.rb
new file mode 100644
index 0000000..5341765
--- /dev/null
+++ b/15/a.rb
@@ -0,0 +1,25 @@
+input = File.read('input.txt').split ','
+
+@t = 1
+
+last_spoken = {}
+last_number = 0
+input.each_with_index do |n, i|
+ if i > 0
+ last_spoken[last_number] = i
+ end
+ last_number = n.to_i
+end
+
+(input.length+1..2020).each do |turn|
+ if !last_spoken[last_number]
+ last_spoken[last_number] = turn - 1
+ last_number = 0
+ else
+ new_last_number = (turn - 1) - last_spoken[last_number]
+ last_spoken[last_number] = turn - 1
+ last_number = new_last_number
+ end
+end
+
+puts last_number
diff --git a/15/b.rb b/15/b.rb
new file mode 100644
index 0000000..7c7b3f9
--- /dev/null
+++ b/15/b.rb
@@ -0,0 +1,25 @@
+input = File.read('input.txt').split ','
+
+@t = 1
+
+last_spoken = {}
+last_number = 0
+input.each_with_index do |n, i|
+ if i > 0
+ last_spoken[last_number] = i
+ end
+ last_number = n.to_i
+end
+
+(input.length+1..30000000).each do |turn|
+ if !last_spoken[last_number]
+ last_spoken[last_number] = turn - 1
+ last_number = 0
+ else
+ new_last_number = (turn - 1) - last_spoken[last_number]
+ last_spoken[last_number] = turn - 1
+ last_number = new_last_number
+ end
+end
+
+puts last_number
diff --git a/15/input.txt b/15/input.txt
new file mode 100644
index 0000000..bf1ac60
--- /dev/null
+++ b/15/input.txt
@@ -0,0 +1 @@
+0,14,6,20,1,4
--
cgit v1.2.3