Solved day 2

day02/input.test

@@ -0,0 +1,3 @@
+A Y
+B X
+C Z

day02/solution.rb

@@ -0,0 +1,102 @@
+#!/bin/env ruby
+require 'pry'
+
+def score(opponent, me)
+  base = case me
+         when :rock
+           1
+         when :paper
+           2
+         when :scissors
+           3
+         end
+  return 3 + base if opponent == me
+
+  outcome = 0
+  outcome = 6 if opponent == :rock and me == :paper
+  outcome = 6 if opponent == :paper and me == :scissors
+  outcome = 6 if opponent == :scissors and me == :rock
+
+  outcome + base
+end
+
+input = File.readlines('./input').map(&:strip)
+
+guide = input.map do |pair|
+  pair.split.map do |letter|
+    case letter
+    when 'A', 'X'
+      :rock
+    when 'B', 'Y'
+      :paper
+    when 'C', 'Z'
+      :scissors
+    end
+  end
+end
+
+scores = guide.map do |pair|
+  score(pair[0], pair[1])
+end
+
+puts "Part 1 Solution: #{scores.sum}"
+
+## Part 2
+def wins_to?(throw)
+  case throw
+  when :rock
+    :paper
+  when :paper
+    :scissors
+  when :scissors
+    :rock
+  end
+end
+
+def loses_to?(throw)
+  case throw
+  when :rock
+    :scissors
+  when :paper
+    :rock
+  when :scissors
+    :paper
+  end
+end
+
+guide2 = input.map do |pair|
+  pair.split.map do |letter|
+    case letter
+    when 'A'
+      :rock
+    when 'B'
+      :paper
+    when 'C'
+      :scissors
+    when 'X'
+      :lose
+    when 'Y'
+      :draw
+    when 'Z'
+      :win
+    end
+  end
+end
+
+guide2.map! do |opponent, outcome|
+  throw = case outcome
+          when :draw
+            opponent
+          when :win
+            wins_to?(opponent)
+          when :lose
+            loses_to?(opponent)
+          end
+  [opponent, throw]
+end
+
+scores2 = guide2.map do |pair|
+  score(pair[0], pair[1])
+end
+
+puts "Part 2 Solution: #{scores2.sum}"