Mikamai Coding Contest: #3

gistfile1.rb

class Maze
  BREADCRUMBS = '.'
  WALKABLE    = ' '
  WALL        = 'X'
  DEAD_END    = 'D'

  attr_reader :map, :coords

  def initialize(map)
    @map    = map
    @coords = to_a
  end

  def draw_path
    coords.each_with_index do |row, y|
      row.each_with_index do |icon, x|
        @y, @x = y, x
        walk
      end
    end
  end

  def to_a
    rows.inject([]) do |board, row|
      board << row.split(//).inject([]) {|arr, icon| arr << icon}
    end
  end

  def to_s
    coords.inject('') do |maze, row|
      maze << "#{row.join}\n"
    end.gsub(DEAD_END, ' ')
  end

  def walk
    if current_position == WALKABLE
      coords[@y][@x] = walkable? ? BREADCRUMBS : DEAD_END
    end
  end

  def rows
    @rows ||= map.split("\n")
  end

  def width
    rows.first.size
  end

  def walkable?
    nearby_coords.select do |position|
      [WALL, DEAD_END].include? get(position)
    end.size < 3
  end

  def current_position
    get [@y, @x]
  end

  def get(coord)
    coords[coord.first][coord.last]
  end

  def nearby_coords
    [[@y-1, @x], [@y+1, @x], [@y, @x-1], [@y, @x+1]]
  end
end


require 'rspec'

map = <<-MAZE
XXXXXXXXXXXX
#   XXX X  o
XXX X X X XX
XX        XX
XXXXXXXXXXXX
MAZE

solution = <<-MAZE
XXXXXXXXXXXX
#...XXX X..o
XXX.X X X.XX
XX .......XX
XXXXXXXXXXXX
MAZE

describe Maze do
  subject { Maze.new(map) }

  it 'assings map' do
    subject.map.should == map
  end

  describe '#rows' do
    it 'splits map in rows' do
      subject.rows.size.should == 5
    end
  end

  describe '#width' do
    it 'returns the map width' do
      subject.width.should == 12
    end
  end

  describe '#to_a' do
    it 'returns bidimensional array' do
      subject.to_a.should be_an(Array)
      subject.to_a.first.should be_an(Array)
    end
  end

  describe '#to_s' do
    it 'returns a string' do
      subject.to_s.should be_a(String)
    end

    context 'when path has not been walked yet' do
      it 'returns original map' do
        subject.to_s.should == map
      end
    end
  end

  describe '#coords' do
    it 'returns the maze in array format' do
      subject.coords.should == subject.to_a
    end
  end

  describe '#get' do
    it 'wraps array access to coords' do
      subject.get([1,2]).should == subject.coords[1][2]
    end
  end

  describe '#current_position' do
    it 'should return the icon in the current position' do
      subject.instance_eval { @x, @y = 11, 1 }
      subject.current_position.should == 'o'
    end
  end

  describe '#nearby_coords' do
    it 'returns an array of coordinates' do
      subject.instance_eval { @x, @y = 2, 1}
      subject.nearby_coords.should =~ [[0, 2], [2, 2], [1, 1], [1,3]]
    end
  end

  describe '#walkable?' do
    context 'when the coord is surrounded by 3 or more walls/dead ends' do
      it 'is false' do
        subject.instance_eval {@x, @y = 2, 3}
        subject.should_not be_walkable
      end
    end

    context 'when the coord is surrounded by less than 3 walls/dead ends' do
      it 'is true' do
        subject.instance_eval {@x, @y = 1, 1}
        subject.should be_walkable
      end
    end
  end

  describe '#walk' do
    context 'when the coord is walkable' do
      it 'should change it to breadcrumbs icon' do
        subject.instance_eval { @x, @y = 1, 1 }
        subject.walk
        subject.get([1, 1]).should == '.'
      end
    end
  end

  describe '#draw_path' do
    it 'should draw the path to exit' do
      subject.draw_path
      subject.to_s.should == solution
    end
  end
end


puts Maze.new(map).tap {|bc| bc.draw_path}.to_s


require 'benchmark'

Benchmark.bm do |bm|
  bm.report 'Andrea Longhi' do
    10000.times { Maze.new(map).draw_path }
  end
end