martian_rovers

app.rb

require_relative "./rover"

input_array = []
file = ARGV[0]
raise "Not specified input file!" if file.to_s.empty?

File.open(file, "r") do |f|
  f.each_line { |line| input_array << line }
end

plateau_upper_right = input_array[0].split(" ")

RIGHT_LIMIT = plateau_upper_right[0].to_i
UPPER_LIMIT = plateau_upper_right[1].to_i

def run_rovers(input)
  input.delete_at(0)
  rovers = []

  input.each_index do |index|
    if index % 2 == 0
      rover_input = input[index].split(" ")
      rover_x = rover_input[0].to_i
      rover_y = rover_input[1].to_i
      rover_face = rover_input[2]

      rovers[index] = Rover.new(rover_x, rover_y, rover_face)
    else
      instructions = input[index].split("")
      instructions.each { |instruction| follow_instruction(instruction, rovers[index-1]) }

      puts "#{rovers[index-1].x} #{rovers[index-1].y} #{rovers[index-1].facing}"
    end
  end
end

def follow_instruction(instruction, rover)
  case instruction
  when "L" then rover.turn_left
  when "R" then rover.turn_right
  when "M" then rover.move_forward
  end
end

run_rovers(input_array)

input.txt

5 5
1 2 N
LMLMLMLMM
3 3 E
MMRMMRMRRM

rover.rb

class Rover
  attr_accessor :x, :y, :facing

  def initialize(x, y, facing)
    @x = x
    @y = y
    @facing = facing
  end

  def turn_left
    case @facing
      when "N" then @facing = "W"
      when "S" then @facing = "E"
      when "E" then @facing = "N"
      when "W" then @facing = "S"
    end
  end

  def turn_right
    case @facing
      when "N" then @facing = "E"
      when "S" then @facing = "W"
      when "E" then @facing = "S"
      when "W" then @facing = "N"
    end
  end

  def move_forward
    case @facing
      when "N"
        @y += 1 if @y < UPPER_LIMIT
      when "S"
        @y -=1 if @y > 0
      when "E"
        @x += 1 if @x < RIGHT_LIMIT
      when "W"
        @x -= 1 if @x > 0
    end
  end
end