“Связанный список в Ruby” Ответ

Связанный список в Ruby

# Full explanation & credit in the source link 

# ----- The Node class for linked list

class Node
  attr_accessor :next
  attr_reader   :value
  def initialize(value)
    @value = value
    @next  = nil
  end
  def to_s
    "Node with value: #{@value}"
  end
end

# ----- The LinkedList class

class LinkedList
  def initialize
    @head = nil
  end
  def append(value)
    if @head
      find_tail.next = Node.new(value)
    else
      @head = Node.new(value)
    end
  end
  def find_tail
    node = @head
    return node if !node.next
    return node if !node.next while (node = node.next)
  end
  def append_after(target, value)
    node           = find(target)
    return unless node
    old_next       = node.next
    node.next      = Node.new(value)
    node.next.next = old_next
  end
  def find(value)
    node = @head
    return false if !node.next
    return node  if node.value == value
    while (node = node.next)
      return node if node.value == value
    end
  end
  def delete(value)
    if @head.value == value
      @head = @head.next
      return
    end
    node      = find_before(value)
    node.next = node.next.next
  end
  def find_before(value)
    node = @head
    return false if !node.next
    return node  if node.next.value == value
    while (node = node.next)
      return node if node.next && node.next.value == value
    end
  end
  def print
    node = @head
    puts node
    while (node = node.next)
      puts node
    end
  end
end

# ----- an example 

list = LinkedList.new
list.append(10)
list.append(20)
list.append(30)
list.append_after(10, 15)
list.append_after(20, 25)
list.print # ---> 10, 15, 20, 25, 30