Question

我接受了一个代码挑战，即使用以下密码信息获取用户输入并转换该输入：

replace = {
  "A" => "Z",
  "B" => "Y",
  "C" => "X",
  "D" => "W",
  "E" => "V",
  "F" => "U",
  "G" => "T",
  "H" => "S",
  "I" => "R",
  "J" => "Q",
  "K" => "P",
  "L" => "O",
  "M" => "N",
  "N" => "M",
  "O" => "L",
  "P" => "K",
  "Q" => "K",
  "R" => "I",
  "S" => "H",
  "T" => "G",
  "U" => "F",
  "V" => "E",
  "W" => "D",
  "X" => "C",
  "Y" => "B",
  "Z" => "A"
}

这是我的代码：

puts "Time to decipher some code: "
input = gets.chomp.upcase
replace.each do |k, v| 
  input.gsub!(k,v)
end
puts input

在我的each区块中，我的密码似乎没有正确转换。任何人都可以解释为什么会这样吗？

Answer 1

您正在遍历哈希replace而不是input字符串。那么，如果你的input = "HELLO" ......

Input: HELLO
Input: HVLLO
Input: SVLLO
Input: SVOOO
Input: SVLLL   #changing back O to L
Input: HVLLL   #changing back S to H
Input: HELLL   #changing back V to E

由于您正在重复replace，因此您最终会多次切换字母。

我对此问题的解决办法是迭代input中的每个字母，然后根据replace替换它们。为了遍历input，我必须将其拆分，然后最终将其加入到字符串中。

Answer 2

您的问题不是特定于Ruby的。这是一个非常非常非常基本（学校）级别的算法错误。你得到了你的结果，因为被替换的角色可以在以后匹配，用其他东西替换。

当人们有变量a = "foo"和b = "bar"并且正在尝试切换他们的值时，它会让人联想到错误：

b = a
a = b

正确执行此操作的典型方法是：

input.gsub!(/./, Hash.new{|_, k| k}.merge(replace))

Answer 3

input = gets.chomp.upcase
p input.gsub(/[A-Z]/, replace)

神秘的/[A-Z]/部分是一个正则表达式，它在字符串中搜索任何大写字符。然后gsub将其替换为replace哈希中的内容。

Answer 4

尝试这样的事情：

replace = {
  "A" => "Z",
  "B" => "Y",
  "C" => "X",
  "D" => "W",
  "E" => "V",
  "F" => "U",
  "G" => "T",
  "H" => "S",
  "I" => "R",
  "J" => "Q",
  "K" => "P",
  "L" => "O",
  "M" => "N",
  "N" => "M",
  "O" => "L",
  "P" => "K",
  "Q" => "K",
  "R" => "I",
  "S" => "H",
  "T" => "G",
  "U" => "F",
  "V" => "E",
  "W" => "D",
  "X" => "C",
  "Y" => "B",
  "Z" => "A"
}

puts "Time to decipher some code: "
input = gets.chomp.upcase

output = ""
input.each_char do |c|
    output << replace[c]
end
puts output

Answer 5

感谢大家的帮助！我能够使用你的很多帖子来解决它，但拉曼似乎是最简单的。

replace = {
  "A" => "Z",
  "B" => "Y",
  "C" => "X",
  "D" => "W",
  "E" => "V",
  "F" => "U",
  "G" => "T",
  "H" => "S",
  "I" => "R",
  "J" => "Q",
  "K" => "P",
  "L" => "O",
  "M" => "N",
  "N" => "M",
  "O" => "L",
  "P" => "K",
  "Q" => "K",
  "R" => "I",
  "S" => "H",
  "T" => "G",
  "U" => "F",
  "V" => "E",
  "W" => "D",
  "X" => "C",
  "Y" => "B",
  "Z" => "A"
}

puts "Time to decipher some code: "
input = gets.chomp.upcase

output = ""
input.each_char do |c|
    output << replace[c]
end

puts output

获取用户输入字符串并将其转换为哈希

5 个答案: