2022 day 3 - part 1

Author: Robb Kidd

2022/ruby/day03.rb

@@ -0,0 +1,45 @@
+class Day03
+  def self.go
+    day = new
+    puts "Part 1: #{day.part1}"
+    puts "Part 2: #{day.part2}"
+  end
+
+  def initialize(input=nil)
+    @input = input || real_input
+  end
+
+  PRIORITIES = [nil] + ('a'..'z').to_a + ('A'..'Z').to_a
+
+  # @example
+  #   day.part1 #=> 157
+  def part1
+    @input
+      .split("\n")
+      .map{ |line| line.chars }
+      .map{ |items| items
+        .each_slice( (items.length/2.0).floor )
+        .to_a
+        .reduce(&:&)
+      }
+      .flatten
+      .map{ |common_item| PRIORITIES.index(common_item) }
+      .reduce(&:+)
+  end
+
+  def part2
+  end
+
+  def real_input
+    File.read('../inputs/day03-input.txt')
+  end
+
+  EXAMPLE_INPUT = <<~INPUT
+    vJrwpWtwJgWrhcsFMMfFFhFp
+    jqHRNqRjqzjGDLGLrsFMfFZSrLrFZsSL
+    PmmdzqPrVvPwwTWBwg
+    wMqvLMZHhHMvwLHjbvcjnnSBnvTQFn
+    ttgJtRGJQctTZtZT
+    CrZsJsPPZsGzwwsLwLmpwMDw
+  INPUT
+end