如何解决 Ruby Wizardry“留在循环中”的示例程序？答案

【问题标题】：How to solve Ruby Wizardry "Staying in the loop" example program?如何解决 Ruby Wizardry“留在循环中”的示例程序？
【发布时间】：2019-05-19 02:16:09
【问题描述】：

Ruby Wizardry Chapter 4 一书包含以下示例程序

we_wanna_ride = true
stops = ["East Bumpspark", "Endertromb Avenue", "New Mixico", "Mal Abochny"]

while we_wanna_ride
    print "Where ya headin', friend?"
    destination = gets.chomp
    if stops.include? destination
    puts "I know how to get to #{destination}! Here's the station list:"
        stops.each do |stop|
            puts stop
            break if stop == destination
        end
    else
        puts "Sorry, we don't stop at that station. Maybe another time!"
        we_wanna_ride = false
    end
end

接下来会带来一些额外的挑战：

“如果乘客在火车上朝另一方向行驶（例如，从 Mal Abochny 到 East Bumpspark）怎么办？如何更新程序以双向工作？更棘手的是，如果火车路线是大圆圈（意思是如果乘客从 East Bumpspark 到 Mal Abochny，Mal Abochny 之后的下一站应该又是 East Bumpspark）？如果乘客想去所有地方，你如何更新程序以打印出正确的火车停靠点列表绕圈的路？”

有人知道如何在这里进行吗？我是一个初级程序员，所以任何帮助将不胜感激。这是我到目前为止的进展。我想我会从用户那里得到一个departure，然后使用 to.i 将输入变成一个整数。然后我可以使用整数值与数组中的索引位置进行比较。如果骑手想朝相反的方向前进，我可以使用 stop.each.reverse 之类的东西以相反的顺序打印出数组项。

we_wanna_ride = true
stops = ["East Bumpspark(1)", "Endertromb Avenue(2)", "New Mixico(3)", "Mal Abochny(4)"]
puts "#{stops}"

while we_wanna_ride
    print "Select a destination number"
    destination = gets.chomp.to_i
    print "Select a departure number"
    departure = gets.chomp.to_i
    if departure <= destination
        stops.each do |stop|
            puts stop
            break if stop == destination
        end
    else puts "Sorry"
    we_wanna_ride = false
    end
end

【问题讨论】：

如果您发布您所做的尝试而不是完全开放式的问题，通常更容易获得答案。试一试并编辑您的问题，包括您的尝试、您期望的工作以及发生了什么。
谢谢@Max！我希望我的新描述更有用。干杯

标签： arrays ruby loops while-loop

【解决方案1】：

以下是我解决这一挑战的方法。它有效，但相当冗长。更高级的 ruby 编码器可能能够提供更短的解决方案：

    we_wanna_ride = true
stops = ["East Bumpspark", "Endertromb Avenue", "New Mixico", "Mal Abochny"]

while we_wanna_ride
  print "Where do you wish to depart from?: "
  depart = gets.chomp.split.map(&:capitalize).join(' ')
  depart_index = stops.index(depart)
#  puts depart_index

  print "Where ya headin' friend?: "
  destination = gets.chomp.split.map(&:capitalize).join(' ')
  destination_index = stops.index(destination)
#  puts destination_index

  index_diff1 = depart_index - destination_index
  index_diff2 = destination_index - depart_index

  if stops.include? destination && depart
    puts "\nI know how to get to #{destination}! Here's the station list:"

    if destination_index > depart_index && index_diff2 < 3
      stops[depart_index..-1].each do |stop|
        puts stop
        break if stop == destination
      end
    we_wanna_ride = false

    elsif destination_index > depart_index && index_diff2 >= 3
      dubstops = stops.concat(stops)
      dubstops[0..depart_index+4].reverse_each do |stop|
        puts stop
        break if stop == destination
      end
    we_wanna_ride = false

    elsif destination_index < depart_index && index_diff1 < 3
      stops[0..depart_index].reverse_each do |stop|
        puts stop
        break if stop == destination
      end
    we_wanna_ride = false

    elsif destination_index < depart_index && index_diff1 >= 3
      dubstops = stops.concat(stops)
      dubstops[depart_index..-1].each do |stop|
        puts stop
        break if stop == destination
      end
    we_wanna_ride = false
    end

  else
    puts "Sorry, we don't service that station. Maybe another time!"
    we_wanna_ride = false
  end
end

【讨论】：