remove_duplicates.rb

def remove_duplicates(string)
  write_index = 0

  for i in 0..string.length-1
    found = false

    for j in 0..write_index-1
      if (string[i] == string[j])
        found = true
        break
      end
    end

    unless found
      string[write_index] = string[i]
      write_index += 1
    end
  end
  string[0, write_index]
end

p remove_duplicates('abbabcddbabcdeedebc')