ruby 火星探测器的问题

Posted 2021-05-16

## MARS ROVER TEST ##

# A squad of robotic rovers are to be landed by NASA on a plateau on Mars. This plateau, which is curiously rectangular, must be navigated by the rovers so that their on-board cameras can get a complete view of the surrounding terrain to send back to Earth.

# A rover's position and location is represented by a combination of x and y co-ordinates and a letter representing one of the four cardinal compass points. The plateau is divided up into a grid to simplify navigation. An example position might be 0, 0, N, which means the rover is in the bottom left corner and facing North.

# In order to control a rover, NASA sends a simple string of letters. The possible letters are 'L', 'R' and 'M'. 'L' and 'R' makes the rover spin 90 degrees left or right respectively, without moving from its current spot. 'M' means move forward one grid point, and maintain the same heading.

# Assume that the square directly North from (x, y) is (x, y+1).

# INPUT
# The first line of input is the upper-right coordinates of the plateau, the lower-left coordinates are assumed to be 0,0.

# The rest of the input is information pertaining to the rovers that have been deployed. Each rover has two lines of input. The first line gives the rover's position, and the second line is a series of instructions telling the rover how to explore the plateau.

# The position is made up of two integers and a letter separated by spaces, corresponding to the x and y co-ordinates and the rover's orientation.

# Each rover will be finished sequentially, which means that the second rover won't start to move until the first one has finished moving.

# OUTPUT
# The output for each rover should be its final co-ordinates and heading.

# INPUT AND OUTPUT

# Test Input:
# 5 5
# 1 2 N
# LMLMLMLMM
# 3 3 E
# MMRMMRMRRM

# Expected Output:
# 1 3 N
# 5 1 E
# ___


class Rover

  def initialize(cords, heading)
    @rover_x, @rover_y = cords
    @rover_heading = heading
  end

  def turn(direction)
    @rover_heading = case @rover_heading
    when 'N' then (direction == :left) ? 'W' : 'E'
    when 'E' then (direction == :left) ? 'N' : 'S'
    when 'S' then (direction == :left) ? 'E' : 'W'
    when 'W' then (direction == :left) ? 'S' : 'N'
    end
  end

  def move
    case @rover_heading
    when 'N' then @rover_y += 1
    when 'E' then @rover_x += 1
    when 'S' then @rover_y -= 1
    when 'W' then @rover_x -= 1
    end
  end

  def run_command(cmd)
    case cmd
    when "L" then turn(:left)
    when "R" then turn(:right)
    when "M" then move
    else
      raise "Invalid command #{cmd}"
    end
  end

  def to_s
    "#{@rover_x} #{@rover_y} #{@rover_heading}"
  end
end


class RoverIO
  include Enumerable

  def initialize(file_path = nil)
    @io = file_path ? File.open(file_path) : STDIN
    @top_right_cords = @io.gets.split.map(&:to_i)
  end

  def get_input
    rover_compass_cords = @io.gets
    return nil unless rover_compass_cords
    rover_cords = rover_compass_cords.chop.split[0...2].map(&:to_i)
    rover_heading = rover_compass_cords.chop.split.last
    commands = @io.gets.chop.split('')
    return nil unless commands
    [rover_cords, rover_heading, commands]
  end

  def each &block
    while args = get_input
      break unless args
      if block_given?
        block.call args
      else
        yield args
      end
    end
  end
end

input = ENV['VEL_DEV'] ? 'rover.inputs' : nil
RoverIO.new(input).each do |rover_cords, rover_heading, commands|
  rover = Rover.new(rover_cords, rover_heading)
  commands.each{|cmd| rover.run_command(cmd)}
  STDOUT.puts rover
end