Day 10 Ruby solutions

Author: creideiki

10-1.rb

@@ -0,0 +1,79 @@
+#!/usr/bin/env ruby
+
+require 'numo/narray'
+
+class Map
+  attr_reader :map, :visited
+
+  def initialize(input)
+    @height = input.size
+    @width = input[0].size
+    @trailheads = []
+    @peaks = []
+    @map = Numo::UInt8.zeros(@height, @width)
+    @height.times do |y|
+      @width.times do |x|
+        case input[y][x]
+        when '.'
+          @map[y, x] = 255
+        when '0'
+          @map[y, x] = 0
+          @trailheads << [y, x]
+        when '9'
+          @map[y, x] = 9
+          @peaks << [y, x]
+        else
+          @map[y, x] = input[y][x].to_i
+        end
+      end
+    end
+  end
+
+  def trace(y, x, visited)
+    return 0 if visited[y, x] == 1
+
+    visited[y, x] = 1
+    cur_height = @map[y, x]
+
+    return 1 if cur_height == 9
+
+    score  = 0
+    score += trace(y + 1, x, visited) if y + 1 < @height && @map[y + 1, x] == cur_height + 1
+    score += trace(y - 1, x, visited) if y - 1 >= 0 && @map[y - 1, x] == cur_height + 1
+    score += trace(y, x + 1, visited) if x + 1 < @width && @map[y, x + 1] == cur_height + 1
+    score += trace(y, x - 1, visited) if x - 1 >= 0 && @map[y, x - 1] == cur_height + 1
+    score
+  end
+
+  def hike
+    score = 0
+    @trailheads.each do |t|
+      score += trace(t[0], t[1], Numo::UInt8.zeros(@height, @width))
+    end
+    score
+  end
+
+  def inspect
+    to_s
+  end
+
+  def to_s
+    s = "<#{self.class}:\n"
+    @height.times do |y|
+      @width.times do |x|
+        s += case @map[y, x]
+             when 255
+               '.'
+             else
+               @map[y, x].to_s
+             end
+      end
+      s += "\n"
+    end
+    s += '>'
+    s
+  end
+end
+
+map = Map.new File.read('10.input').lines.map(&:strip)
+puts map.hike

10-2.rb

@@ -0,0 +1,78 @@
+#!/usr/bin/env ruby
+
+require 'numo/narray'
+
+class Map
+  attr_reader :map, :visited
+
+  def initialize(input)
+    @height = input.size
+    @width = input[0].size
+    @trailheads = []
+    @peaks = []
+    @map = Numo::UInt8.zeros(@height, @width)
+    @height.times do |y|
+      @width.times do |x|
+        case input[y][x]
+        when '.'
+          @map[y, x] = 255
+        when '0'
+          @map[y, x] = 0
+          @trailheads << [y, x]
+        when '9'
+          @map[y, x] = 9
+          @peaks << [y, x]
+        else
+          @map[y, x] = input[y][x].to_i
+        end
+      end
+    end
+  end
+
+  def trace(y, x, visited)
+    return 0 if visited.include? [y, x]
+
+    cur_height = @map[y, x]
+
+    return 1 if cur_height == 9
+
+    score  = 0
+    score += trace(y + 1, x, visited + [y, x]) if y + 1 < @height && @map[y + 1, x] == cur_height + 1
+    score += trace(y - 1, x, visited + [y, x]) if y - 1 >= 0 && @map[y - 1, x] == cur_height + 1
+    score += trace(y, x + 1, visited + [y, x]) if x + 1 < @width && @map[y, x + 1] == cur_height + 1
+    score += trace(y, x - 1, visited + [y, x]) if x - 1 >= 0 && @map[y, x - 1] == cur_height + 1
+    score
+  end
+
+  def hike
+    score = 0
+    @trailheads.each do |t|
+      score += trace(t[0], t[1], [])
+    end
+    score
+  end
+
+  def inspect
+    to_s
+  end
+
+  def to_s
+    s = "<#{self.class}:\n"
+    @height.times do |y|
+      @width.times do |x|
+        s += case @map[y, x]
+             when 255
+               '.'
+             else
+               @map[y, x].to_s
+             end
+      end
+      s += "\n"
+    end
+    s += '>'
+    s
+  end
+end
+
+map = Map.new File.read('10.input').lines.map(&:strip)
+puts map.hike