Day 8 Ruby solutions

Author: creideiki

08-1.rb

@@ -0,0 +1,87 @@
+#!/usr/bin/env ruby
+
+require 'numo/narray'
+
+class Map
+  attr_reader :antennae, :map, :antinodes
+
+  def initialize(input)
+    @height = input.size
+    @width = input[0].size
+    @antennae = Hash.new []
+    @map = Numo::UInt8.zeros(@height, @width)
+    @antinodes = Numo::UInt8.zeros(@height, @width)
+    @height.times do |y|
+      @width.times do |x|
+        case input[y][x]
+        when '.'
+          @map[y, x] = 0
+        else
+          @map[y, x] = input[y][x].codepoints[0]
+          @antennae[input[y][x].codepoints[0]] += [[y, x]]
+        end
+      end
+    end
+  end
+
+  def find_antinodes(a, b)
+    possibles = [
+      [
+        a[0] + (b[0] - a[0]) * 2,
+        a[1] + (b[1] - a[1]) * 2
+      ],
+      [
+        b[0] + (a[0] - b[0]) * 2,
+        b[1] + (a[1] - b[1]) * 2
+      ]
+    ]
+
+    possibles.reject { |p| p[0] < 0 || p[0] >= @height || p[1] < 0 || p[1] >= @width }
+  end
+
+  def fill!
+    antennae.each_value do |ants|
+      ants.combination(2) do |pair|
+        find_antinodes(pair[0], pair[1]).each do |a|
+          @antinodes[a[0], a[1]] += 1
+        end
+      end
+    end
+  end
+
+  def score
+    count = 0
+    @height.times do |y|
+      @width.times do |x|
+        count += 1 if @antinodes[y, x].positive?
+      end
+    end
+    count
+  end
+
+  def inspect
+    to_s
+  end
+
+  def to_s
+    s  = "<#{self.class}:\n"
+    @height.times do |y|
+      @width.times do |x|
+        if @map[y, x] != 0
+          s << @map[y, x]
+        elsif @antinodes[y, x] != 0
+          s += '#'
+        else
+          s += '.'
+        end
+      end
+      s += "\n"
+    end
+    s += ">"
+    s
+  end
+end
+
+map = Map.new File.read('08.input').lines.map(&:strip)
+map.fill!
+puts map.score

08-2.rb

@@ -0,0 +1,97 @@
+#!/usr/bin/env ruby
+
+require 'numo/narray'
+
+class Map
+  attr_reader :antennae, :map, :antinodes
+
+  def initialize(input)
+    @height = input.size
+    @width = input[0].size
+    @antennae = Hash.new []
+    @map = Numo::UInt8.zeros(@height, @width)
+    @antinodes = Numo::UInt8.zeros(@height, @width)
+    @height.times do |y|
+      @width.times do |x|
+        case input[y][x]
+        when '.'
+          @map[y, x] = 0
+        else
+          @map[y, x] = input[y][x].codepoints[0]
+          @antennae[input[y][x].codepoints[0]] += [[y, x]]
+        end
+      end
+    end
+  end
+
+  def find_antinodes(a, b)
+    dy = b[0] - a[0]
+    dx = b[1] - a[1]
+
+    possibles = [a, b]
+
+    y = a[0] + dy * 2
+    x = a[1] + dx * 2
+    while y < @height && x < @width && y >= 0 && x >= 0
+      possibles << [y, x]
+      y += dy
+      x += dx
+    end
+
+    y = a[0] - dy
+    x = a[1] - dx
+    while y < @height && x < @width && y >= 0 && x >= 0
+      possibles << [y, x]
+      y -= dy
+      x -= dx
+    end
+
+    possibles
+  end
+
+  def fill!
+    antennae.each_value do |ants|
+      ants.combination(2) do |pair|
+        find_antinodes(pair[0], pair[1]).each do |a|
+          @antinodes[a[0], a[1]] += 1
+        end
+      end
+    end
+  end
+
+  def score
+    count = 0
+    @height.times do |y|
+      @width.times do |x|
+        count += 1 if @antinodes[y, x].positive?
+      end
+    end
+    count
+  end
+
+  def inspect
+    to_s
+  end
+
+  def to_s
+    s  = "<#{self.class}:\n"
+    @height.times do |y|
+      @width.times do |x|
+        if @map[y, x] != 0
+          s << @map[y, x]
+        elsif @antinodes[y, x] != 0
+          s += '#'
+        else
+          s += '.'
+        end
+      end
+      s += "\n"
+    end
+    s += ">"
+    s
+  end
+end
+
+map = Map.new File.read('08.input').lines.map(&:strip)
+map.fill!
+puts map.score