Basic exercises with Ruby

fizz_buzz.rb

[*1..100].each do |number|
  text = ""
  text << "fizz " if number % 3 == 0
  text << "buzz " if number % 5 == 0
  unless text.empty?
    puts text
  else
    puts number
  end
end

index_sort.rb

class IndexSort
  def self.sort(ary, ascend=true)
    ary_ = []
    ary.each do |num|
      ary_[num] = num
    end
    ary_ = ary_.select { |value| !value.nil? }
    ascend ? ary_ : ary_.reverse
  end
end

linked_list.rb

class LinkedList
  ITEM = Struct.new :prev, :next, :content

  def initialize(content)
    @hsh = {}
    @hsh[0] = ITEM.new(nil, nil, content)
    @hsh[0].content = content
  end

  def add(element)
    if element.instance_of? LinkedList
      element.contents.each do |value|
        add_content value
      end
    else
      add_content element
    end
  end

  def delete(index)
    item = @hsh[index]
    @hsh[item.prev].next = item.next
    @hsh[item.next].prev = item.prev
    item.prev = nil
    item.next = nil
  end

  def contents
    @hsh.values.collect(&:content)
  end

  def deleted?(item)
    item.prev.nil? && item.next.nil?
  end

  def last
    @hsh.each_pair.select { |index, item | !deleted?(item) && item.next.nil? }.first.last.content
  end

  def first
    @hsh.each_pair.select { |index, item | !deleted?(item) && item.prev.nil? }.first.last.content
  end

private
  def add_content(content)
    index = @hsh.length
    @hsh[index-1].next = index if index > 1
    @hsh[index] = ITEM.new(index-1, nil, content)
  end
end