重复次数

Question

  

编写一个接受字符串的方法，并返回在字符串中出现多次的字母数。您可以假设该字符串仅包含小写字母。计算重复的字母数，而不是它们在字符串中重复的次数。

我将方法和测试用例实现为：

def num_repeats(string)
  count = 0
  dix = 0
  new = ""
  while dix < string.length
    letter = string[dix]
    if !(new.include?(letter))
      new = new + "letter"
    else
      break
    end
    dix2 = dix + 1
    while dix2 < string.length
      if letter == string[dix2]
        count +=1
        break
      end
      dix2 +=1
    end
    dix += 1
  end
     puts(count.to_s)
  return count


end

# These are tests to check that your code is working. After writing
# your solution, they should all print true.

puts('num_repeats("abdbc") == 1: ' + (num_repeats('abdbc') == 1).to_s)
# one character is repeated
puts('num_repeats("aaa") == 1: ' + (num_repeats('aaa') == 1).to_s)
puts('num_repeats("abab") == 2: ' + (num_repeats('abab') == 2).to_s)
puts('num_repeats("cadac") == 2: ' + (num_repeats('cadac') == 2).to_s)
puts('num_repeats("abcde") == 0: ' + (num_repeats('abcde') == 0).to_s)

测试结果：

1                                                                                                                                                                                      
num_repeats("abdbc") == 1: true                                                                                                                                                        
2                                                                                                                                                                                      
num_repeats("aaa") == 1: false                                                                                                                                                         
2                                                                                                                                                                                      
num_repeats("abab") == 2: true                                                                                                                                                         
2                                                                                                                                                                                      
num_repeats("cadac") == 2: true                                                                                                                                                        
0                                                                                                                                                                                      
num_repeats("abcde") == 0: true 

对于返回false的第二个测试，我的代码有什么问题？

Answer 1

您要将第{8}行"letter"而不是letter变量附加到new。

if !(new.include?(letter))
  new = new + "letter"
else
  #...
end

变为：

unless new.include?(letter)
  new = new + letter
else
  #...
end