82 lines
4.2 KiB
Markdown
82 lines
4.2 KiB
Markdown
|
---
|
||
|
|
id: 587d825a367417b2b2512c87
|
||
|
|
title: Create a Doubly Linked List
|
||
|
|
challengeType: 1
|
||
|
|
videoUrl: ''
|
||
|
|
localeTitle: 创建双向链接列表
|
||
|
|
---
|
||
|
|
|
||
|
|
## Description
|
||
|
|
<section id="description">到目前为止，我们创建的所有链接列表都是单链表。在这里，我们将创建一个<dfn>双向链表</dfn> 。顾名思义，双向链表中的节点引用了列表中的下一个和上一个节点。这允许我们在两个方向上遍历列表，但它还需要使用更多内存，因为每个节点必须包含对列表中前一个节点的附加引用。 </section>
|
||
|
|
|
||
|
|
## Instructions
|
||
|
|
<section id="instructions">我们提供了一个<code>Node</code>对象并启动了我们的<code>DoublyLinkedList</code> 。让我们将两个方法添加到名为<code>add</code> and <code>remove</code>双向链表<code>remove</code> 。 <code>add</code>方法应该将给定元素添加到列表中，而<code>remove</code>方法应该删除列表中所有出现的给定元素。编写这些方法时要小心处理任何可能的边缘情况，例如删除第一个或最后一个元素。此外，删除空列表中的任何项应返回<code>null</code> 。 </section>
|
||
|
|
|
||
|
|
## Tests
|
||
|
|
<section id='tests'>
|
||
|
|
|
||
|
|
```yml
|
||
|
|
tests:
|
||
|
|
- text: 存在DoublyLinkedList数据结构。
|
||
|
|
testString: 'assert((function() { var test = false; if (typeof DoublyLinkedList !== "undefined") { test = new DoublyLinkedList() }; return (typeof test == "object")})(), "The DoublyLinkedList data structure exists.");'
|
||
|
|
- text: DoublyLinkedList有一个名为add的方法。
|
||
|
|
testString: 'assert((function() { var test = false; if (typeof DoublyLinkedList !== "undefined") { test = new DoublyLinkedList() }; if (test.add == undefined) { return false; }; return (typeof test.add == "function")})(), "The DoublyLinkedList has a method called add.");'
|
||
|
|
- text: DoublyLinkedList有一个名为remove的方法。
|
||
|
|
testString: 'assert((function() { var test = false; if (typeof DoublyLinkedList !== "undefined") { test = new DoublyLinkedList() }; if (test.remove == undefined) { return false; }; return (typeof test.remove == "function")})(), "The DoublyLinkedList has a method called remove.");'
|
||
|
|
- text: 从空列表中删除项目将返回null。
|
||
|
|
testString: 'assert((function() { var test = false; if (typeof DoublyLinkedList !== "undefined") { test = new DoublyLinkedList() }; return (test.remove(100) == null); })(), "Removing an item from an empty list returns null.");'
|
||
|
|
- text: add方法将项添加到列表中。
|
||
|
|
testString: 'assert((function() { var test = false; if (typeof DoublyLinkedList !== "undefined") { test = new DoublyLinkedList() }; test.add(5); test.add(6); test.add(723); return (test.print().join("") == "56723"); })(), "The add method adds items to the list.");'
|
||
|
|
- text: 每个节点都跟踪前一个节点。
|
||
|
|
testString: 'assert((function() { var test = false; if (typeof DoublyLinkedList !== "undefined") { test = new DoublyLinkedList() }; test.add(50); test.add(68); test.add(73); return (test.printReverse().join("") == "736850"); })(), "Each node keeps track of the previous node.");'
|
||
|
|
- text: 可以从列表中删除第一个项目。
|
||
|
|
testString: 'assert((function() { var test = false; if (typeof DoublyLinkedList !== "undefined") { test = new DoublyLinkedList() }; test.add(25); test.add(35); test.add(60); test.remove(25); return ( test.print().join("") == "3560" ) })(), "The first item can be removed from the list.");'
|
||
|
|
- text: 最后一项可以从列表中删除。
|
||
|
|
testString: 'assert((function() { var test = false; if (typeof DoublyLinkedList !== "undefined") { test = new DoublyLinkedList() }; test.add(25); test.add(35); test.add(60); test.remove(60); return ( test.print().join("") == "2535" ) })(), "The last item can be removed from the list.");'
|
||
|
|
|
||
|
|
```
|
||
|
|
|
||
|
|
</section>
|
||
|
|
|
||
|
|
## Challenge Seed
|
||
|
|
<section id='challengeSeed'>
|
||
|
|
|
||
|
|
<div id='js-seed'>
|
||
|
|
|
||
|
|
```js
|
||
|
|
var Node = function(data, prev) {
|
||
|
|
this.data = data;
|
||
|
|
this.prev = prev;
|
||
|
|
this.next = null;
|
||
|
|
};
|
||
|
|
var DoublyLinkedList = function() {
|
||
|
|
this.head = null;
|
||
|
|
this.tail = null;
|
||
|
|
// change code below this line
|
||
|
|
// change code above this line
|
||
|
|
};
|
||
|
|
|
||
|
|
```
|
||
|
|
|
||
|
|
</div>
|
||
|
|
|
||
|
|
|
||
|
|
### After Test
|
||
|
|
<div id='js-teardown'>
|
||
|
|
|
||
|
|
```js
|
||
|
|
console.info('after the test');
|
||
|
|
```
|
||
|
|
|
||
|
|
</div>
|
||
|
|
|
||
|
|
</section>
|
||
|
|
|
||
|
|
## Solution
|
||
|
|
<section id='solution'>
|
||
|
|
|
||
|
|
```js
|
||
|
|
// solution required
|
||
|
|
```
|
||
|
|
</section>
|