dedupe.md

Challenge

Given a string which contains only lowercase letters, remove duplicate consecutive letters so that every letter appear once and only once.

Easy Solution

The right answer in Ruby is to use String#squeeze:

>> "abbaaaaccc".squeeze('a-z')
=> "abac"
>> "abbaa".squeeze('a-z')
=> "aba"

Academic solution

If you want to solve the problem academically, the approach to use is essentially recursively walking the string and comparing letters, slicing off duplicates as you go.

def dedupe(str)
  return if str.empty?

  str.split('').each_with_index do |char, i|
    if str[i] == str[i + 1]
      str.slice!(i + 1)
      return dedupe(str)
    end
  end

  str
end

>> dedupe "abbaaaaccc"
=> "abac"