112 lines
4.0 KiB
Markdown
112 lines
4.0 KiB
Markdown
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---
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id: 587d8251367417b2b2512c64
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title: Search within a Linked List
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challengeType: 1
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videoUrl: ''
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localeTitle: 在链接列表中搜索
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---
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## Description
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<section id="description">让我们为链表类添加一些更有用的方法。如果我们可以判断我们的列表是否为空,那么它是否有用,就像我们的<code>Stack</code>和<code>Queue</code>类一样?我们还应该能够在链表中找到特定元素。遍历数据结构是你想要进行大量练习的东西!让我们创建一个<code>indexOf</code>方法,该方法将<code>element</code>作为参数,并在链表中返回该元素的<code>index</code> 。如果在链接列表中找不到该元素,则返回<code>-1</code> 。让我们实现一个相反的方法:一个<code>elementAt</code>方法,它将<code>index</code>作为参数并返回给定<code>index</code>处的<code>element</code> 。如果未找到任何<code>element</code> ,则返回<code>undefined</code> 。 </section>
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## Instructions
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<section id="instructions">编写一个检查链表是否为空的<code>isEmpty</code>方法,返回给定元素<code>index</code>的<code>indexOf</code>方法,以及返回给定<code>index.</code>处<code>element</code>的<code>elementAt</code> <code>index.</code> </section>
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## Tests
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<section id='tests'>
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```yml
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tests:
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- text: 您的<code>LinkedList</code>类应该有一个<code>indexOf</code>方法。
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testString: 'assert((function(){var test = new LinkedList(); return (typeof test.indexOf === "function")}()), "Your <code>LinkedList</code> class should have a <code>indexOf</code> method.");'
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- text: 您的<code>LinkedList</code>类应该有一个<code>elementAt</code>方法。
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testString: 'assert((function(){var test = new LinkedList(); return (typeof test.elementAt === "function")}()), "Your <code>LinkedList</code> class should have a <code>elementAt</code> method.");'
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- text: 您的<code>size</code>方法应返回链表的长度
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testString: 'assert((function(){var test = new LinkedList(); test.add("cat"); test.add("dog"); test.add("kitten"); return test.size() === 3}()), "Your <code>size</code> method should return the length of the linked list");'
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- text: <code>indexOf</code>方法应该返回给定元素的索引。
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testString: 'assert((function(){var test = new LinkedList(); test.add("cat"); test.add("dog"); test.add("kitten"); return test.indexOf("kitten") === 2}()), "Your <code>indexOf</code> method should return the index of the given element.");'
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- text: 您的<code>elementAt</code>方法应该返回给定索引处的元素。
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testString: 'assert((function(){var test = new LinkedList(); test.add("cat"); test.add("dog"); test.add("kitten"); return test.elementAt(1) === "dog"}()), "Your <code>elementAt</code> method should return at element at a given index.");'
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```
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</section>
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## Challenge Seed
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<section id='challengeSeed'>
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<div id='js-seed'>
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```js
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function LinkedList() {
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var length = 0;
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var head = null;
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var Node = function(element){ // {1}
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this.element = element;
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this.next = null;
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};
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this.size = function() {
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return length;
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};
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this.head = function(){
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return head;
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};
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this.add = function(element){
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var node = new Node(element);
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if(head === null){
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head = node;
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} else {
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currentNode = head;
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while(currentNode.next){
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currentNode = currentNode.next;
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}
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currentNode.next = node;
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}
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length++;
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};
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this.remove = function(element){
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var currentNode = head;
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var previousNode;
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if(currentNode.element === element){
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head = currentNode.next;
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} else {
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while(currentNode.element !== element) {
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previousNode = currentNode;
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currentNode = currentNode.next;
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}
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previousNode.next = currentNode.next;
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}
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length --;
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};
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// Only change code below this line
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// Only change code above this line
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}
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```
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</div>
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</section>
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## Solution
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<section id='solution'>
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```js
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// solution required
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```
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</section>
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