Add solution for 2015 day 10

2015/README.md

@@ -9,8 +9,8 @@
 - [x] Day 06
 - [x] Day 07
 - [x] Day 08
-- [ ] Day 09
+- [x] Day 09
-- [ ] Day 10
+- [x] Day 10
 - [ ] Day 11
 - [ ] Day 12
 - [ ] Day 13

2015/day-10/.ruby-version

@@ -0,0 +1 @@
+3.0.0

2015/day-10/inputs/puzzle.txt

@@ -0,0 +1 @@
+1321131112

2015/day-10/inputs/test.txt

@@ -0,0 +1 @@
+111221

2015/day-10/main.rb

@@ -0,0 +1,42 @@
+#!/usr/bin/env ruby
+# frozen_string_literal: true
+
+require "pathname"
+require "stringio"
+
+def look_and_say(input)
+  counter = 1
+
+  output = input.each_char.map(&:to_i).chain([nil]).each_cons(2).reduce(StringIO.new) do |acc, (val1, val2)|
+    if val1 == val2
+      counter += 1
+    else
+      acc.write counter
+      acc.write val1
+      counter = 1
+    end
+
+    acc
+  end
+
+  output.rewind
+  output
+end
+
+def solve_part1(content)
+  puts 40.times.reduce(StringIO.new(content)) { |acc| look_and_say(acc) }.size
+end
+
+def solve_part2(content)
+  puts 50.times.reduce(StringIO.new(content)) { |acc, _| look_and_say(acc) }.size
+end
+
+def main(files)
+  files.each do |file|
+    content = file.read.chomp
+    solve_part1(content)
+    solve_part2(content)
+  end
+end
+
+main(ARGV.map { |x| Pathname(x) })