Question

我有一个学校作业，我必须在Ruby中找到给定字符串中最长的相邻相等字符。我的程序没有最后一个循环正常工作，但一旦我添加它给了我错误：

(repl):47: syntax error, unexpected keyword_end
(repl):53: syntax error, unexpected end-of-input, expecting keyword_end
puts longestRun
               ^

这是我的代码

puts 'What is your string?'
givenString = gets.chomp

def maxBlock(str)  
  maxRun = 0  
  currentRun = 1  
  characterCounter = 1

  if str.length == 0
    maxRun = 0
    #If no input, longest run is zero

  elsif str.length == 1  
    maxRun = 1
    #If string is one character, longest run is 1

  elsif str.length == 2 and str[characterCounter] != str[characterCounter + 1]
    maxRun = 1
    #if string is two chars and they do not equal, longest run is 1

  elsif str.length == 3 and str[0] != str[1] and str[1] != str[2]
    maxRun = 1
    #if string is three chars and they do not equal, longest run is 1

  else
    str.each_char do|st|
      #Go through each char, compare it to the next, find longest run
      if st == str[characterCounter]
        currentRun++
        if currentRun > maxRun
          maxRun = currentRun
        end
      else
        currentRun = 1
      end
      characterCounter++
    end
  end
end
longestRun = maxBlock(givenString)
puts longestRun

编辑：我是一名高中生，只具备编程基础知识。

编辑：我刚犯了一些愚蠢的错误。我感谢大家的帮助。这是我的工作程序，没有使用太复杂的东西。

puts 'What is your string?'
givenString = gets.chomp

def maxBlock(str)  
  maxRun = 0  
  currentRun = 1  
  characterCounter = 0

  if str.length == 0
    maxRun = 0
    #If no input, longest run is zero

  elsif str.length == 1  
    maxRun = 1
    #If string is one character, longest run is 1

  elsif str.length == 2 and str[characterCounter] != str[characterCounter + 1]
    maxRun = 1
    #if string is two chars and they do not equal, longest run is 1

  elsif str.length == 3 and str[0] != str[1] and str[1] != str[2]
    maxRun = 1
    #if string is three chars and they do not equal, longest run is 1

  else  
    characterCounter += 1
    str.each_char do|st|
      #Go through each char, compare it to the next, find longest run
      if st == str[characterCounter]
        currentRun += 1
        if currentRun > maxRun
          maxRun = currentRun
        end
      else
        currentRun = 1
      end
      characterCounter += 1
    end
  end
return maxRun
end
longestRun = maxBlock(givenString)
puts longestRun

Answer 1

字符串扫描和排序

有这方面的算法，但Ruby提供了一些不错的快捷方式。例如：

def longest_string str
  str.scan(/((\p{Alnum})\2+)/).collect { |grp1, grp2| grp1 }.sort_by(&:size).last
end

longest_string 'foo baaar quuuux'
#=> "uuuu"

这基本上只捕获重复字符的所有运行，按长度对捕获的子字符串进行排序，然后返回长度排序数组的最后一个元素。

二级排序

如果您要进行辅助排序，例如先按长度排序，然后按字母顺序排序，则可以使用Enumerable#sort_by的块形式替换Enumerable#sort。例如：

def longest_string str
  str.scan(/((\p{Alnum})\2+)/).
    collect { |grp1, grp2| grp1 }.
    sort {|a, b| [a.size, a] <=> [b.size, b] }.
    last
end

longest_string 'foo quux baar'
#=> "uu"

Answer 2

这是你可以做到的一种方式。

str = "111 wwwwwwwwaabbbbbbbbbbb$$$$****"

r = /
    (.) # Match any character in capture group 1
    \1* # Match the contents of capture group 1 zero or more times
    /x  # Free-spacing regex definition mode

str.gsub(r).max_by(&:size)
  #=> "bbbbbbbbbbb"

我使用了String#gsub的形式而没有第二个参数或块，因为它返回一个生成与正则表达式匹配的字符串的枚举器。然后我将该枚举器链接到方法Enumerable#max_by以找到最长的连续字符串。换句话说，我只使用gsub来生成匹配而不是执行替换。

当然可以写str.gsub(/(.)\1*/).max_by(&:size)。

Answer 3

以下是适用于所有情况的简化版本：

puts 'What is your string?'
given_string = gets.chomp

def max_block(str)  
  max_run = 0
  current_run = 1

  str.each_char.with_index do |st, idx|
    if st == str[idx + 1]
      current_run += 1
    else
      current_run = 1
    end

    max_run = current_run if current_run > max_run
  end

  max_run
end

longest_run = max_block(given_string)
puts longest_run

你走在正确的轨道上，但Ruby可以让你的事情变得更轻松。注意with_index如何摆脱很多复杂性。迭代器，哦，是的。

我还将您的方法名称和变量更改为camel_case。

快乐的编码！

Ruby中最长的运行程序

3 个答案:

字符串扫描和排序

二级排序