2022 day 4 part 1

Author: Robb Kidd

2022/ruby/day04.rb

@@ -0,0 +1,45 @@
+class Day04
+  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
+
+  # @example
+  #   day.part1 => 2
+  def part1
+    @input
+      .split("\n")
+      .map { |line| line.split(",") }
+      .map { |pair| 
+        pair
+          .map{ |elf| elf.split("-").map(&:to_i)}
+          .map{ |start, stop| Range.new(start,stop) }
+      }
+      .map { |assign_a, assign_b|
+        assign_a.cover?(assign_b) || assign_b.cover?(assign_a)
+      }
+      .select {|fully_contains| fully_contains == true }
+      .count
+  end
+
+  def part2
+  end
+
+  def real_input
+    File.read('../inputs/day04-input.txt')
+  end
+
+  EXAMPLE_INPUT = <<~INPUT
+    2-4,6-8
+    2-3,4-5
+    5-7,7-9
+    2-8,3-7
+    6-6,4-6
+    2-6,4-8
+  INPUT
+end