使用ruby

Question

您好我试图在ruby的链接列表中的特定索引处插入一个值。

到目前为止，这是我的代码：

class Node
  attr_accessor :data, :pointer, :next

  def initialize(data, pointer = nil)
    @data = data
    @pointer = pointer
  end

  def next
    @data = @pointer
  end

end

class LinkedList
  attr_accessor :head, :data, :pointer

  def initialize(data)
    @head = Node.new(data, pointer)
  end

  def index_at(value_of_index)
    current = head
    value_of_index.times do 
      if current.pointer == nil
        current = Node.new(nil, nil)
        return current = current.data
      else
        current = current.next
      end
    end
    current.data
  end

  def insert_at_index(index, value)
    current = head
    index.times do
      current.next
    end
    current = Node.new(value)
  end
end

我遇到的问题是使用def insert_at_index方法......我似乎无法弄清楚如何将新节点放在索引和值上。您将给予我的任何帮助将不胜感激。

Answer 1

假设您的链接列表如下所示：

a -> b -> d -> e

要将c插入第3个索引，您将移至第二个索引以获取b，创建新节点，在新节点{{旁边设置b 1}}，并在旧的第三个索引项c旁边设置c。

这会给你：

d

那就是说，代码应该是这样的：

a -> b -> c -> d -> e

从它的外观来看，你的代码似乎还有其他问题。你在下一个函数中覆盖了def insert_at_index(index, value) current = head # make current b. You may want to put this in a function node_at_index (index - 1).times do raise "List not long enough" if current.nil? current = current.next end new_node = Node.new(value) # new node c new_node.next = current.next # c's next is b's next, d current.next = new_node # b's next is c end （你可能只是@data}，return @pointer没有定义LinkedList#initialize等等

您可以将Node简化为：

pointer

哪个应该适合你。

Answer 2

这是一个对我有用的解决方案：

class Node
  attr_accessor :data, :pointer
  alias_method :next, :pointer

  def initialize(data, pointer = nil)
    @data = data
    @pointer = pointer
  end

  def next
    @pointer
  end

end

class LinkedList
  attr_accessor :head, :data, :pointer

  def initialize(data)
    @head = Node.new(data, pointer)
  end

  def index_at(value_of_index)
    current = head
    value_of_index.times do 
      if current.pointer == nil
        current = Node.new(nil, nil)
        return current = current.data
      else
        current = current.next
      end
    end
    current.data
  end

  def insert_at_index(index, value)
    current = head

    (index - 1).times do
      if current.pointer != nil
      current = current.next
      end
    end
    new_node = Node.new(value)
    if current.pointer != nil
      new_node.pointer = current.pointer
    end
    current.pointer = new_node
  end

end