75 lines
3.1 KiB
Markdown
75 lines
3.1 KiB
Markdown
---
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id: 587d8257367417b2b2512c7b
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title: Add a New Element to a Binary Search Tree
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challengeType: 1
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videoUrl: ''
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localeTitle: 将新元素添加到二叉搜索树
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---
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## Description
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<section id="description">现在我们已经了解了基础知识，让我们编写一个更复杂的方法。在此挑战中，我们将创建一个向二叉搜索树添加新值的方法。该方法应该被称为<code>add</code> ，它应该接受一个整数值来添加到树中。注意保持二叉搜索树的不变量：每个左子项中的值应小于或等于父值，并且每个右子项中的值应大于或等于父值。在这里，让我们这样做，以便我们的树不能容纳重复的值。如果我们尝试添加已存在的值，则该方法应返回<code>null</code> 。否则，如果添加成功，则应返回<code>undefined</code> 。提示：树是自然递归的数据结构！ </section>
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## Instructions
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<section id="instructions">
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</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: 存在<code>BinarySearchTree</code>数据结构。
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testString: 'assert((function() { var test = false; if (typeof BinarySearchTree !== "undefined") { test = new BinarySearchTree() }; return (typeof test == "object")})(), "The <code>BinarySearchTree</code> data structure exists.");'
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- text: 二叉搜索树有一个名为<code>add</code>的方法。
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testString: 'assert((function() { var test = false; if (typeof BinarySearchTree !== "undefined") { test = new BinarySearchTree() } else { return false; }; return (typeof test.add == "function")})(), "The binary search tree has a method called <code>add</code>.");'
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- text: add方法根据二叉搜索树规则添加元素。
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testString: 'assert((function() { var test = false; if (typeof BinarySearchTree !== "undefined") { test = new BinarySearchTree() } else { return false; }; if (typeof test.add !== "function") { return false; }; test.add(4); test.add(1); test.add(7); test.add(87); test.add(34); test.add(45); test.add(73); test.add(8); const expectedResult = [ 1, 4, 7, 8, 34, 45, 73, 87 ]; const result = test.inOrder(); return (expectedResult.toString() === result.toString()); })(), "The add method adds elements according to the binary search tree rules.");'
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- text: 添加已存在的元素将返回<code>null</code>
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testString: 'assert((function() { var test = false; if (typeof BinarySearchTree !== "undefined") { test = new BinarySearchTree() } else { return false; }; if (typeof test.add !== "function") { return false; }; test.add(4); return test.add(4) == null; })(), "Adding an element that already exists returns <code>null</code>");'
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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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var displayTree = (tree) => console.log(JSON.stringify(tree, null, 2));
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function Node(value) {
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this.value = value;
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this.left = null;
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this.right = null;
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}
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function BinarySearchTree() {
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this.root = null;
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// change code below this line
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// change code above this line
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}
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```
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</div>
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### After Test
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<div id='js-teardown'>
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```js
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console.info('after the test');
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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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