22 lines
47 KiB
HTML
22 lines
47 KiB
HTML
<!doctype html>
|
||
<html lang="en" dir="ltr" class="docs-wrapper docs-doc-page docs-version-current plugin-docs plugin-id-default docs-doc-id-book1/algorithm-balanced-binary-trees">
|
||
<head>
|
||
<meta charset="UTF-8">
|
||
<meta name="generator" content="Docusaurus v2.3.1">
|
||
<title data-rh="true">平衡二叉树 | HZFE - 剑指前端 Offer</title><meta data-rh="true" name="viewport" content="width=device-width,initial-scale=1"><meta data-rh="true" name="twitter:card" content="summary_large_image"><meta data-rh="true" property="og:url" content="https://febook.hzfe.org/awesome-interview/book1/algorithm-balanced-binary-trees"><meta data-rh="true" name="docusaurus_locale" content="en"><meta data-rh="true" name="docsearch:language" content="en"><meta data-rh="true" name="docusaurus_version" content="current"><meta data-rh="true" name="docusaurus_tag" content="docs-default-current"><meta data-rh="true" name="docsearch:version" content="current"><meta data-rh="true" name="docsearch:docusaurus_tag" content="docs-default-current"><meta data-rh="true" property="og:title" content="平衡二叉树 | HZFE - 剑指前端 Offer"><meta data-rh="true" name="description" content="题目描述"><meta data-rh="true" property="og:description" content="题目描述"><link data-rh="true" rel="icon" href="/awesome-interview/img/favicon.ico"><link data-rh="true" rel="canonical" href="https://febook.hzfe.org/awesome-interview/book1/algorithm-balanced-binary-trees"><link data-rh="true" rel="alternate" href="https://febook.hzfe.org/awesome-interview/book1/algorithm-balanced-binary-trees" hreflang="en"><link data-rh="true" rel="alternate" href="https://febook.hzfe.org/awesome-interview/book1/algorithm-balanced-binary-trees" hreflang="x-default"><link data-rh="true" rel="preconnect" href="https://PED5MQGL7T-dsn.algolia.net" crossorigin="anonymous"><link rel="search" type="application/opensearchdescription+xml" title="HZFE - 剑指前端 Offer" href="/awesome-interview/opensearch.xml">
|
||
<link rel="apple-touch-icon" href="/awesome-interview/img/badge.png">
|
||
<link rel="manifest" href="/awesome-interview/manifest.json">
|
||
<link rel="preconnect" href="https://hm.baidu.com">
|
||
<script>var _hmt=_hmt||[];!function(){var e=document.createElement("script");e.src="https://hm.baidu.com/hm.js?c7cd0fd77ac518cc6ef46461cdc9524b";var c=document.getElementsByTagName("script")[0];c.parentNode.insertBefore(e,c)}()</script>
|
||
<script src="https://pagead2.googlesyndication.com/pagead/js/adsbygoogle.js" async data-ad-client="ca-pub-9889934432771967"></script>
|
||
<script src="https://pagead2.googlesyndication.com/pagead/js/adsbygoogle.js?client=ca-pub-9889934432771967" async crossorigin="anonymous"></script><link rel="stylesheet" href="/awesome-interview/assets/css/styles.0f62048e.css">
|
||
<link rel="preload" href="/awesome-interview/assets/js/runtime~main.a75952d5.js" as="script">
|
||
<link rel="preload" href="/awesome-interview/assets/js/main.a5e14537.js" as="script">
|
||
</head>
|
||
<body class="navigation-with-keyboard">
|
||
<script>!function(){function t(t){document.documentElement.setAttribute("data-theme",t)}var e=function(){var t=null;try{t=localStorage.getItem("theme")}catch(t){}return t}();t(null!==e?e:"light")}()</script><div id="__docusaurus">
|
||
<div role="region" aria-label="Skip to main content"><a class="skipToContent_fXgn" href="#docusaurus_skipToContent_fallback">Skip to main content</a></div><nav aria-label="Main" class="navbar navbar--fixed-top navbarHideable_m1mJ"><div class="navbar__inner"><div class="navbar__items"><button aria-label="Toggle navigation bar" aria-expanded="false" class="navbar__toggle clean-btn" type="button"><svg width="30" height="30" viewBox="0 0 30 30" aria-hidden="true"><path stroke="currentColor" stroke-linecap="round" stroke-miterlimit="10" stroke-width="2" d="M4 7h22M4 15h22M4 23h22"></path></svg></button><a class="navbar__brand" href="/awesome-interview/"><div class="navbar__logo"><img src="/awesome-interview/img/badge.svg" alt="HZFE" class="themedImage_ToTc themedImage--light_HNdA"><img src="/awesome-interview/img/badge.svg" alt="HZFE" class="themedImage_ToTc themedImage--dark_i4oU"></div><b class="navbar__title text--truncate">剑指前端 Offer</b></a></div><div class="navbar__items navbar__items--right"><a href="https://github.com/hzfe/awesome-interview" target="_blank" rel="noopener noreferrer" class="navbar__item navbar__link">GitHub<svg width="13.5" height="13.5" aria-hidden="true" viewBox="0 0 24 24" class="iconExternalLink_nPIU"><path fill="currentColor" d="M21 13v10h-21v-19h12v2h-10v15h17v-8h2zm3-12h-10.988l4.035 4-6.977 7.07 2.828 2.828 6.977-7.07 4.125 4.172v-11z"></path></svg></a><div class="searchBox_ZlJk"><button type="button" class="DocSearch DocSearch-Button" aria-label="Search"><span class="DocSearch-Button-Container"><svg width="20" height="20" class="DocSearch-Search-Icon" viewBox="0 0 20 20"><path d="M14.386 14.386l4.0877 4.0877-4.0877-4.0877c-2.9418 2.9419-7.7115 2.9419-10.6533 0-2.9419-2.9418-2.9419-7.7115 0-10.6533 2.9418-2.9419 7.7115-2.9419 10.6533 0 2.9419 2.9418 2.9419 7.7115 0 10.6533z" stroke="currentColor" fill="none" fill-rule="evenodd" stroke-linecap="round" stroke-linejoin="round"></path></svg><span class="DocSearch-Button-Placeholder">Search</span></span><span class="DocSearch-Button-Keys"></span></button></div></div></div><div role="presentation" class="navbar-sidebar__backdrop"></div></nav><div id="docusaurus_skipToContent_fallback" class="main-wrapper mainWrapper_z2l0 docsWrapper_BCFX"><button aria-label="Scroll back to top" class="clean-btn theme-back-to-top-button backToTopButton_sjWU" type="button"></button><div class="docPage__5DB"><aside class="theme-doc-sidebar-container docSidebarContainer_b6E3"><div class="sidebarViewport_Xe31"><div class="sidebar_njMd sidebarWithHideableNavbar_wUlq"><a tabindex="-1" class="sidebarLogo_isFc" href="/awesome-interview/"><img src="/awesome-interview/img/badge.svg" alt="HZFE" class="themedImage_ToTc themedImage--light_HNdA"><img src="/awesome-interview/img/badge.svg" alt="HZFE" class="themedImage_ToTc themedImage--dark_i4oU"><b>剑指前端 Offer</b></a><nav aria-label="Docs sidebar" class="menu thin-scrollbar menu_SIkG"><ul class="theme-doc-sidebar-menu menu__list"><li class="theme-doc-sidebar-item-link theme-doc-sidebar-item-link-level-1 menu__list-item"><a class="menu__link" href="/awesome-interview/about">关于我们</a></li><li class="theme-doc-sidebar-item-link theme-doc-sidebar-item-link-level-1 menu__list-item"><a class="menu__link" href="/awesome-interview/">前言</a></li><li class="theme-doc-sidebar-item-category theme-doc-sidebar-item-category-level-1 menu__list-item"><div class="menu__list-item-collapsible"><a class="menu__link menu__link--sublist menu__link--sublist-caret menu__link--active" aria-expanded="true" href="/awesome-interview/book1/browser-cross-origin">模拟题一</a></div><ul style="display:block;overflow:visible;height:auto" class="menu__list"><li class="theme-doc-sidebar-item-link theme-doc-sidebar-item-link-level-2 menu__list-item"><a class="menu__link" tabindex="0" href="/awesome-interview/book1/browser-cross-origin">浏览器:浏览器跨域</a></li><li class="theme-doc-sidebar-item-link theme-doc-sidebar-item-link-level-2 menu__list-item"><a class="menu__link" tabindex="0" href="/awesome-interview/book1/browser-repain-reflow">浏览器:浏览器的重排重绘</a></li><li class="theme-doc-sidebar-item-link theme-doc-sidebar-item-link-level-2 menu__list-item"><a class="menu__link" tabindex="0" href="/awesome-interview/book1/engineer-webpack-workflow">工程化:webpack 工作流程</a></li><li class="theme-doc-sidebar-item-link theme-doc-sidebar-item-link-level-2 menu__list-item"><a class="menu__link" tabindex="0" href="/awesome-interview/book1/frame-vue-data-binding">框架:Vue 的数据绑定机制</a></li><li class="theme-doc-sidebar-item-link theme-doc-sidebar-item-link-level-2 menu__list-item"><a class="menu__link" tabindex="0" href="/awesome-interview/book1/frame-vue-computed-watch">框架:Vue 的 computed 和 watch 的区别</a></li><li class="theme-doc-sidebar-item-link theme-doc-sidebar-item-link-level-2 menu__list-item"><a class="menu__link" tabindex="0" href="/awesome-interview/book1/js-closures">基础:闭包的作用和原理</a></li><li class="theme-doc-sidebar-item-link theme-doc-sidebar-item-link-level-2 menu__list-item"><a class="menu__link" tabindex="0" href="/awesome-interview/book1/js-module-specs">基础:前端模块化规范</a></li><li class="theme-doc-sidebar-item-link theme-doc-sidebar-item-link-level-2 menu__list-item"><a class="menu__link" tabindex="0" href="/awesome-interview/book1/css-bfc">样式:BFC 的形成和作用</a></li><li class="theme-doc-sidebar-item-link theme-doc-sidebar-item-link-level-2 menu__list-item"><a class="menu__link" tabindex="0" href="/awesome-interview/book1/network-security">网络:前端安全</a></li><li class="theme-doc-sidebar-item-link theme-doc-sidebar-item-link-level-2 menu__list-item"><a class="menu__link" tabindex="0" href="/awesome-interview/book1/coding-promise">编码:实现一个符合 Promises/A+ 规范的 Promise</a></li><li class="theme-doc-sidebar-item-link theme-doc-sidebar-item-link-level-2 menu__list-item"><a class="menu__link menu__link--active" aria-current="page" tabindex="0" href="/awesome-interview/book1/algorithm-balanced-binary-trees">算法:平衡二叉树</a></li><li class="theme-doc-sidebar-item-link theme-doc-sidebar-item-link-level-2 menu__list-item"><a class="menu__link" tabindex="0" href="/awesome-interview/book1/topic-enter-url-display-xx">综合:浏览器从输入网址到页面展现的过程</a></li></ul></li><li class="theme-doc-sidebar-item-category theme-doc-sidebar-item-category-level-1 menu__list-item menu__list-item--collapsed"><div class="menu__list-item-collapsible"><a class="menu__link menu__link--sublist menu__link--sublist-caret" aria-expanded="false" href="/awesome-interview/book2/browser-render-mechanism">模拟题二</a></div></li><li class="theme-doc-sidebar-item-category theme-doc-sidebar-item-category-level-1 menu__list-item menu__list-item--collapsed"><div class="menu__list-item-collapsible"><a class="menu__link menu__link--sublist menu__link--sublist-caret" aria-expanded="false" href="/awesome-interview/book3/browser-event-loop">模拟题三</a></div></li><li class="theme-doc-sidebar-item-category theme-doc-sidebar-item-category-level-1 menu__list-item menu__list-item--collapsed"><div class="menu__list-item-collapsible"><a class="menu__link menu__link--sublist menu__link--sublist-caret" aria-expanded="false" href="/awesome-interview/book4/browser-router">模拟题四</a></div></li></ul></nav><button type="button" title="Collapse sidebar" aria-label="Collapse sidebar" class="button button--secondary button--outline collapseSidebarButton_PEFL"><svg width="20" height="20" aria-hidden="true" class="collapseSidebarButtonIcon_kv0_"><g fill="#7a7a7a"><path d="M9.992 10.023c0 .2-.062.399-.172.547l-4.996 7.492a.982.982 0 01-.828.454H1c-.55 0-1-.453-1-1 0-.2.059-.403.168-.551l4.629-6.942L.168 3.078A.939.939 0 010 2.528c0-.548.45-.997 1-.997h2.996c.352 0 .649.18.828.45L9.82 9.472c.11.148.172.347.172.55zm0 0"></path><path d="M19.98 10.023c0 .2-.058.399-.168.547l-4.996 7.492a.987.987 0 01-.828.454h-3c-.547 0-.996-.453-.996-1 0-.2.059-.403.168-.551l4.625-6.942-4.625-6.945a.939.939 0 01-.168-.55 1 1 0 01.996-.997h3c.348 0 .649.18.828.45l4.996 7.492c.11.148.168.347.168.55zm0 0"></path></g></svg></button></div></div></aside><main class="docMainContainer_gTbr"><div class="container padding-top--md padding-bottom--lg"><div class="row"><div class="col docItemCol_VOVn"><div class="docItemContainer_Djhp"><article><nav class="theme-doc-breadcrumbs breadcrumbsContainer_Z_bl" aria-label="Breadcrumbs"><ul class="breadcrumbs" itemscope="" itemtype="https://schema.org/BreadcrumbList"><li class="breadcrumbs__item"><a aria-label="Home page" class="breadcrumbs__link" href="/awesome-interview/"><svg viewBox="0 0 24 24" class="breadcrumbHomeIcon_YNFT"><path d="M10 19v-5h4v5c0 .55.45 1 1 1h3c.55 0 1-.45 1-1v-7h1.7c.46 0 .68-.57.33-.87L12.67 3.6c-.38-.34-.96-.34-1.34 0l-8.36 7.53c-.34.3-.13.87.33.87H5v7c0 .55.45 1 1 1h3c.55 0 1-.45 1-1z" fill="currentColor"></path></svg></a></li><li class="breadcrumbs__item"><span class="breadcrumbs__link">模拟题一</span><meta itemprop="position" content="1"></li><li itemscope="" itemprop="itemListElement" itemtype="https://schema.org/ListItem" class="breadcrumbs__item breadcrumbs__item--active"><span class="breadcrumbs__link" itemprop="name">算法:平衡二叉树</span><meta itemprop="position" content="2"></li></ul></nav><div class="tocCollapsible_ETCw theme-doc-toc-mobile tocMobile_ITEo"><button type="button" class="clean-btn tocCollapsibleButton_TO0P">On this page</button></div><div class="theme-doc-markdown markdown"><h1>平衡二叉树</h1><h2 class="anchor anchorWithHideOnScrollNavbar_WYt5" id="题目描述">题目描述<a href="#题目描述" class="hash-link" aria-label="Direct link to 题目描述" title="Direct link to 题目描述"></a></h2><p>输入一棵二叉树的根节点,判断该树是不是平衡二叉树。如果某二叉树中任意节点的左右子树的深度相差不超过 1,那么它就是一棵平衡二叉树。</p><p>示例 1:</p><div class="codeBlockContainer_Ckt0 theme-code-block" style="--prism-color:#393A34;--prism-background-color:#f6f8fa"><div class="codeBlockContent_biex"><pre tabindex="0" class="prism-code language-text codeBlock_bY9V thin-scrollbar"><code class="codeBlockLines_e6Vv"><span class="token-line" style="color:#393A34"><span class="token plain">给定二叉树 [3, 9, 20, null, null, 15, 7]</span><br></span><span class="token-line" style="color:#393A34"><span class="token plain" style="display:inline-block"></span><br></span><span class="token-line" style="color:#393A34"><span class="token plain"> 3</span><br></span><span class="token-line" style="color:#393A34"><span class="token plain"> / \</span><br></span><span class="token-line" style="color:#393A34"><span class="token plain"> 9 20</span><br></span><span class="token-line" style="color:#393A34"><span class="token plain"> / \</span><br></span><span class="token-line" style="color:#393A34"><span class="token plain"> 15 7</span><br></span><span class="token-line" style="color:#393A34"><span class="token plain">返回 true。</span><br></span></code></pre><div class="buttonGroup__atx"><button type="button" aria-label="Copy code to clipboard" title="Copy" class="clean-btn"><span class="copyButtonIcons_eSgA" aria-hidden="true"><svg class="copyButtonIcon_y97N" viewBox="0 0 24 24"><path d="M19,21H8V7H19M19,5H8A2,2 0 0,0 6,7V21A2,2 0 0,0 8,23H19A2,2 0 0,0 21,21V7A2,2 0 0,0 19,5M16,1H4A2,2 0 0,0 2,3V17H4V3H16V1Z"></path></svg><svg class="copyButtonSuccessIcon_LjdS" viewBox="0 0 24 24"><path d="M21,7L9,19L3.5,13.5L4.91,12.09L9,16.17L19.59,5.59L21,7Z"></path></svg></span></button></div></div></div><p>示例 2:</p><div class="codeBlockContainer_Ckt0 theme-code-block" style="--prism-color:#393A34;--prism-background-color:#f6f8fa"><div class="codeBlockContent_biex"><pre tabindex="0" class="prism-code language-text codeBlock_bY9V thin-scrollbar"><code class="codeBlockLines_e6Vv"><span class="token-line" style="color:#393A34"><span class="token plain">给定二叉树 [1,2,2,3,3,null,null,4,4]</span><br></span><span class="token-line" style="color:#393A34"><span class="token plain" style="display:inline-block"></span><br></span><span class="token-line" style="color:#393A34"><span class="token plain"> 1</span><br></span><span class="token-line" style="color:#393A34"><span class="token plain"> / \</span><br></span><span class="token-line" style="color:#393A34"><span class="token plain"> 2 2</span><br></span><span class="token-line" style="color:#393A34"><span class="token plain"> / \</span><br></span><span class="token-line" style="color:#393A34"><span class="token plain"> 3 3</span><br></span><span class="token-line" style="color:#393A34"><span class="token plain"> / \</span><br></span><span class="token-line" style="color:#393A34"><span class="token plain"> 4 4</span><br></span><span class="token-line" style="color:#393A34"><span class="token plain">返回 false。</span><br></span></code></pre><div class="buttonGroup__atx"><button type="button" aria-label="Copy code to clipboard" title="Copy" class="clean-btn"><span class="copyButtonIcons_eSgA" aria-hidden="true"><svg class="copyButtonIcon_y97N" viewBox="0 0 24 24"><path d="M19,21H8V7H19M19,5H8A2,2 0 0,0 6,7V21A2,2 0 0,0 8,23H19A2,2 0 0,0 21,21V7A2,2 0 0,0 19,5M16,1H4A2,2 0 0,0 2,3V17H4V3H16V1Z"></path></svg><svg class="copyButtonSuccessIcon_LjdS" viewBox="0 0 24 24"><path d="M21,7L9,19L3.5,13.5L4.91,12.09L9,16.17L19.59,5.59L21,7Z"></path></svg></span></button></div></div></div><p>限制:0 <= 树的结点个数 <= 10000</p><h2 class="anchor anchorWithHideOnScrollNavbar_WYt5" id="基本知识点">基本知识点<a href="#基本知识点" class="hash-link" aria-label="Direct link to 基本知识点" title="Direct link to 基本知识点"></a></h2><p>二叉树的每个节点最多有两个子节点,平衡二叉树中任意一个节点的左右子树高度相差不能大于 1,满二叉树和完全二叉树都是平衡二叉树,普通二叉树有可能是平衡二叉树。</p><h2 class="anchor anchorWithHideOnScrollNavbar_WYt5" id="题解">题解<a href="#题解" class="hash-link" aria-label="Direct link to 题解" title="Direct link to 题解"></a></h2><h3 class="anchor anchorWithHideOnScrollNavbar_WYt5" id="解法一">解法一<a href="#解法一" class="hash-link" aria-label="Direct link to 解法一" title="Direct link to 解法一"></a></h3><h4 class="anchor anchorWithHideOnScrollNavbar_WYt5" id="思路">思路<a href="#思路" class="hash-link" aria-label="Direct link to 思路" title="Direct link to 思路"></a></h4><p>若想判断二叉树是不是平衡二叉树,只需要判断左右子树的高度差是不是不超过 1 即可。同时,要满足一个树是平衡二叉树,它的子树也必须是平衡二叉树。我们可以从根结点开始,通过递归来求得子树的高度,以及子树是否是平衡二叉树,以此来结合判断二叉树是否是平衡二叉树。</p><h4 class="anchor anchorWithHideOnScrollNavbar_WYt5" id="代码">代码<a href="#代码" class="hash-link" aria-label="Direct link to 代码" title="Direct link to 代码"></a></h4><div class="language-javascript codeBlockContainer_Ckt0 theme-code-block" style="--prism-color:#393A34;--prism-background-color:#f6f8fa"><div class="codeBlockContent_biex"><pre tabindex="0" class="prism-code language-javascript codeBlock_bY9V thin-scrollbar"><code class="codeBlockLines_e6Vv"><span class="token-line" style="color:#393A34"><span class="token comment" style="color:#999988;font-style:italic">/**</span><br></span><span class="token-line" style="color:#393A34"><span class="token comment" style="color:#999988;font-style:italic"> * Definition for a binary tree node.</span><br></span><span class="token-line" style="color:#393A34"><span class="token comment" style="color:#999988;font-style:italic"> * function TreeNode(val, left, right) {</span><br></span><span class="token-line" style="color:#393A34"><span class="token comment" style="color:#999988;font-style:italic"> * this.val = (val === undefined ? 0 : val)</span><br></span><span class="token-line" style="color:#393A34"><span class="token comment" style="color:#999988;font-style:italic"> * this.left = (left === undefined ? null : left)</span><br></span><span class="token-line" style="color:#393A34"><span class="token comment" style="color:#999988;font-style:italic"> * this.right = (right === undefined ? null : right)</span><br></span><span class="token-line" style="color:#393A34"><span class="token comment" style="color:#999988;font-style:italic"> * }</span><br></span><span class="token-line" style="color:#393A34"><span class="token comment" style="color:#999988;font-style:italic"> */</span><span class="token plain"></span><br></span><span class="token-line" style="color:#393A34"><span class="token plain"></span><span class="token comment" style="color:#999988;font-style:italic">/**</span><br></span><span class="token-line" style="color:#393A34"><span class="token comment" style="color:#999988;font-style:italic"> * @param {TreeNode} root</span><br></span><span class="token-line" style="color:#393A34"><span class="token comment" style="color:#999988;font-style:italic"> * @return {boolean}</span><br></span><span class="token-line" style="color:#393A34"><span class="token comment" style="color:#999988;font-style:italic"> */</span><span class="token plain"></span><br></span><span class="token-line" style="color:#393A34"><span class="token plain"></span><span class="token keyword" style="color:#00009f">const</span><span class="token plain"> </span><span class="token function-variable function" style="color:#d73a49">isBalanced</span><span class="token plain"> </span><span class="token operator" style="color:#393A34">=</span><span class="token plain"> </span><span class="token keyword" style="color:#00009f">function</span><span class="token plain"> </span><span class="token punctuation" style="color:#393A34">(</span><span class="token parameter">root</span><span class="token punctuation" style="color:#393A34">)</span><span class="token plain"> </span><span class="token punctuation" style="color:#393A34">{</span><span class="token plain"></span><br></span><span class="token-line" style="color:#393A34"><span class="token plain"> </span><span class="token keyword control-flow" style="color:#00009f">if</span><span class="token plain"> </span><span class="token punctuation" style="color:#393A34">(</span><span class="token plain">root </span><span class="token operator" style="color:#393A34">===</span><span class="token plain"> </span><span class="token keyword null nil" style="color:#00009f">null</span><span class="token punctuation" style="color:#393A34">)</span><span class="token plain"> </span><span class="token punctuation" style="color:#393A34">{</span><span class="token plain"></span><br></span><span class="token-line" style="color:#393A34"><span class="token plain"> </span><span class="token keyword control-flow" style="color:#00009f">return</span><span class="token plain"> </span><span class="token boolean" style="color:#36acaa">true</span><span class="token punctuation" style="color:#393A34">;</span><span class="token plain"></span><br></span><span class="token-line" style="color:#393A34"><span class="token plain"> </span><span class="token punctuation" style="color:#393A34">}</span><span class="token plain"> </span><span class="token keyword control-flow" style="color:#00009f">else</span><span class="token plain"> </span><span class="token punctuation" style="color:#393A34">{</span><span class="token plain"></span><br></span><span class="token-line" style="color:#393A34"><span class="token plain"> </span><span class="token keyword control-flow" style="color:#00009f">return</span><span class="token plain"> </span><span class="token punctuation" style="color:#393A34">(</span><span class="token plain"></span><br></span><span class="token-line" style="color:#393A34"><span class="token plain"> </span><span class="token known-class-name class-name">Math</span><span class="token punctuation" style="color:#393A34">.</span><span class="token method function property-access" style="color:#d73a49">abs</span><span class="token punctuation" style="color:#393A34">(</span><span class="token function" style="color:#d73a49">height</span><span class="token punctuation" style="color:#393A34">(</span><span class="token plain">root</span><span class="token punctuation" style="color:#393A34">.</span><span class="token property-access">left</span><span class="token punctuation" style="color:#393A34">)</span><span class="token plain"> </span><span class="token operator" style="color:#393A34">-</span><span class="token plain"> </span><span class="token function" style="color:#d73a49">height</span><span class="token punctuation" style="color:#393A34">(</span><span class="token plain">root</span><span class="token punctuation" style="color:#393A34">.</span><span class="token property-access">right</span><span class="token punctuation" style="color:#393A34">)</span><span class="token punctuation" style="color:#393A34">)</span><span class="token plain"> </span><span class="token operator" style="color:#393A34"><=</span><span class="token plain"> </span><span class="token number" style="color:#36acaa">1</span><span class="token plain"> </span><span class="token operator" style="color:#393A34">&&</span><span class="token plain"></span><br></span><span class="token-line" style="color:#393A34"><span class="token plain"> </span><span class="token function" style="color:#d73a49">isBalanced</span><span class="token punctuation" style="color:#393A34">(</span><span class="token plain">root</span><span class="token punctuation" style="color:#393A34">.</span><span class="token property-access">left</span><span class="token punctuation" style="color:#393A34">)</span><span class="token plain"> </span><span class="token operator" style="color:#393A34">&&</span><span class="token plain"></span><br></span><span class="token-line" style="color:#393A34"><span class="token plain"> </span><span class="token function" style="color:#d73a49">isBalanced</span><span class="token punctuation" style="color:#393A34">(</span><span class="token plain">root</span><span class="token punctuation" style="color:#393A34">.</span><span class="token property-access">right</span><span class="token punctuation" style="color:#393A34">)</span><span class="token plain"></span><br></span><span class="token-line" style="color:#393A34"><span class="token plain"> </span><span class="token punctuation" style="color:#393A34">)</span><span class="token punctuation" style="color:#393A34">;</span><span class="token plain"></span><br></span><span class="token-line" style="color:#393A34"><span class="token plain"> </span><span class="token punctuation" style="color:#393A34">}</span><span class="token plain"></span><br></span><span class="token-line" style="color:#393A34"><span class="token plain"></span><span class="token punctuation" style="color:#393A34">}</span><span class="token punctuation" style="color:#393A34">;</span><span class="token plain"></span><br></span><span class="token-line" style="color:#393A34"><span class="token plain" style="display:inline-block"></span><br></span><span class="token-line" style="color:#393A34"><span class="token plain"></span><span class="token keyword" style="color:#00009f">const</span><span class="token plain"> </span><span class="token function-variable function" style="color:#d73a49">height</span><span class="token plain"> </span><span class="token operator" style="color:#393A34">=</span><span class="token plain"> </span><span class="token keyword" style="color:#00009f">function</span><span class="token plain"> </span><span class="token punctuation" style="color:#393A34">(</span><span class="token parameter">root</span><span class="token punctuation" style="color:#393A34">)</span><span class="token plain"> </span><span class="token punctuation" style="color:#393A34">{</span><span class="token plain"></span><br></span><span class="token-line" style="color:#393A34"><span class="token plain"> </span><span class="token keyword control-flow" style="color:#00009f">if</span><span class="token plain"> </span><span class="token punctuation" style="color:#393A34">(</span><span class="token plain">root </span><span class="token operator" style="color:#393A34">===</span><span class="token plain"> </span><span class="token keyword null nil" style="color:#00009f">null</span><span class="token punctuation" style="color:#393A34">)</span><span class="token plain"> </span><span class="token punctuation" style="color:#393A34">{</span><span class="token plain"></span><br></span><span class="token-line" style="color:#393A34"><span class="token plain"> </span><span class="token keyword control-flow" style="color:#00009f">return</span><span class="token plain"> </span><span class="token number" style="color:#36acaa">0</span><span class="token punctuation" style="color:#393A34">;</span><span class="token plain"></span><br></span><span class="token-line" style="color:#393A34"><span class="token plain"> </span><span class="token punctuation" style="color:#393A34">}</span><span class="token plain"> </span><span class="token keyword control-flow" style="color:#00009f">else</span><span class="token plain"> </span><span class="token punctuation" style="color:#393A34">{</span><span class="token plain"></span><br></span><span class="token-line" style="color:#393A34"><span class="token plain"> </span><span class="token keyword control-flow" style="color:#00009f">return</span><span class="token plain"> </span><span class="token known-class-name class-name">Math</span><span class="token punctuation" style="color:#393A34">.</span><span class="token method function property-access" style="color:#d73a49">max</span><span class="token punctuation" style="color:#393A34">(</span><span class="token function" style="color:#d73a49">height</span><span class="token punctuation" style="color:#393A34">(</span><span class="token plain">root</span><span class="token punctuation" style="color:#393A34">.</span><span class="token property-access">left</span><span class="token punctuation" style="color:#393A34">)</span><span class="token punctuation" style="color:#393A34">,</span><span class="token plain"> </span><span class="token function" style="color:#d73a49">height</span><span class="token punctuation" style="color:#393A34">(</span><span class="token plain">root</span><span class="token punctuation" style="color:#393A34">.</span><span class="token property-access">right</span><span class="token punctuation" style="color:#393A34">)</span><span class="token punctuation" style="color:#393A34">)</span><span class="token plain"> </span><span class="token operator" style="color:#393A34">+</span><span class="token plain"> </span><span class="token number" style="color:#36acaa">1</span><span class="token punctuation" style="color:#393A34">;</span><span class="token plain"></span><br></span><span class="token-line" style="color:#393A34"><span class="token plain"> </span><span class="token punctuation" style="color:#393A34">}</span><span class="token plain"></span><br></span><span class="token-line" style="color:#393A34"><span class="token plain"></span><span class="token punctuation" style="color:#393A34">}</span><span class="token punctuation" style="color:#393A34">;</span><br></span></code></pre><div class="buttonGroup__atx"><button type="button" aria-label="Copy code to clipboard" title="Copy" class="clean-btn"><span class="copyButtonIcons_eSgA" aria-hidden="true"><svg class="copyButtonIcon_y97N" viewBox="0 0 24 24"><path d="M19,21H8V7H19M19,5H8A2,2 0 0,0 6,7V21A2,2 0 0,0 8,23H19A2,2 0 0,0 21,21V7A2,2 0 0,0 19,5M16,1H4A2,2 0 0,0 2,3V17H4V3H16V1Z"></path></svg><svg class="copyButtonSuccessIcon_LjdS" viewBox="0 0 24 24"><path d="M21,7L9,19L3.5,13.5L4.91,12.09L9,16.17L19.59,5.59L21,7Z"></path></svg></span></button></div></div></div><h4 class="anchor anchorWithHideOnScrollNavbar_WYt5" id="时间复杂度分析">时间复杂度分析<a href="#时间复杂度分析" class="hash-link" aria-label="Direct link to 时间复杂度分析" title="Direct link to 时间复杂度分析"></a></h4><p>该方法最坏的情况是每个父节点都只有一个子节点,这样树的高度时间复杂度为 O(n),即“链表”的长度。而第 d 层调用 <code>height</code> 函数的时间复杂度是 O(d),所以整体的时间复杂度为高度时间复杂度 <!-- -->*<!-- --> 调用 <code>height</code> 函数的时间复杂度,即 O(n^2)。</p><h4 class="anchor anchorWithHideOnScrollNavbar_WYt5" id="空间复杂度分析">空间复杂度分析<a href="#空间复杂度分析" class="hash-link" aria-label="Direct link to 空间复杂度分析" title="Direct link to 空间复杂度分析"></a></h4><p>空间复杂度取决于递归调用的层数,不会超过 n 层,所以空间复杂度是 O(n)。</p><h3 class="anchor anchorWithHideOnScrollNavbar_WYt5" id="解法二">解法二<a href="#解法二" class="hash-link" aria-label="Direct link to 解法二" title="Direct link to 解法二"></a></h3><h4 class="anchor anchorWithHideOnScrollNavbar_WYt5" id="思路-1">思路<a href="#思路-1" class="hash-link" aria-label="Direct link to 思路" title="Direct link to 思路"></a></h4><p>上面的方法是自顶而下的,这样其实就会导致每层的高度都要重复计算。那么,我们可以使用后序遍历,这样每个节点的高度就能根据前面的结果算出来。</p><h4 class="anchor anchorWithHideOnScrollNavbar_WYt5" id="代码-1">代码<a href="#代码-1" class="hash-link" aria-label="Direct link to 代码" title="Direct link to 代码"></a></h4><div class="language-javascript codeBlockContainer_Ckt0 theme-code-block" style="--prism-color:#393A34;--prism-background-color:#f6f8fa"><div class="codeBlockContent_biex"><pre tabindex="0" class="prism-code language-javascript codeBlock_bY9V thin-scrollbar"><code class="codeBlockLines_e6Vv"><span class="token-line" style="color:#393A34"><span class="token comment" style="color:#999988;font-style:italic">/**</span><br></span><span class="token-line" style="color:#393A34"><span class="token comment" style="color:#999988;font-style:italic"> * Definition for a binary tree node.</span><br></span><span class="token-line" style="color:#393A34"><span class="token comment" style="color:#999988;font-style:italic"> * function TreeNode(val, left, right) {</span><br></span><span class="token-line" style="color:#393A34"><span class="token comment" style="color:#999988;font-style:italic"> * this.val = (val === undefined ? 0 : val)</span><br></span><span class="token-line" style="color:#393A34"><span class="token comment" style="color:#999988;font-style:italic"> * this.left = (left === undefined ? null : left)</span><br></span><span class="token-line" style="color:#393A34"><span class="token comment" style="color:#999988;font-style:italic"> * this.right = (right === undefined ? null : right)</span><br></span><span class="token-line" style="color:#393A34"><span class="token comment" style="color:#999988;font-style:italic"> * }</span><br></span><span class="token-line" style="color:#393A34"><span class="token comment" style="color:#999988;font-style:italic"> */</span><span class="token plain"></span><br></span><span class="token-line" style="color:#393A34"><span class="token plain"></span><span class="token comment" style="color:#999988;font-style:italic">/**</span><br></span><span class="token-line" style="color:#393A34"><span class="token comment" style="color:#999988;font-style:italic"> * @param {TreeNode} root</span><br></span><span class="token-line" style="color:#393A34"><span class="token comment" style="color:#999988;font-style:italic"> * @return {boolean}</span><br></span><span class="token-line" style="color:#393A34"><span class="token comment" style="color:#999988;font-style:italic"> */</span><span class="token plain"></span><br></span><span class="token-line" style="color:#393A34"><span class="token plain"></span><span class="token keyword" style="color:#00009f">var</span><span class="token plain"> </span><span class="token function-variable function" style="color:#d73a49">isBalanced</span><span class="token plain"> </span><span class="token operator" style="color:#393A34">=</span><span class="token plain"> </span><span class="token keyword" style="color:#00009f">function</span><span class="token plain"> </span><span class="token punctuation" style="color:#393A34">(</span><span class="token parameter">root</span><span class="token punctuation" style="color:#393A34">)</span><span class="token plain"> </span><span class="token punctuation" style="color:#393A34">{</span><span class="token plain"></span><br></span><span class="token-line" style="color:#393A34"><span class="token plain"> </span><span class="token keyword control-flow" style="color:#00009f">return</span><span class="token plain"> </span><span class="token function" style="color:#d73a49">height</span><span class="token punctuation" style="color:#393A34">(</span><span class="token plain">root</span><span class="token punctuation" style="color:#393A34">)</span><span class="token plain"> </span><span class="token operator" style="color:#393A34">!=</span><span class="token plain"> </span><span class="token operator" style="color:#393A34">-</span><span class="token number" style="color:#36acaa">1</span><span class="token punctuation" style="color:#393A34">;</span><span class="token plain"></span><br></span><span class="token-line" style="color:#393A34"><span class="token plain"></span><span class="token punctuation" style="color:#393A34">}</span><span class="token punctuation" style="color:#393A34">;</span><span class="token plain"></span><br></span><span class="token-line" style="color:#393A34"><span class="token plain" style="display:inline-block"></span><br></span><span class="token-line" style="color:#393A34"><span class="token plain"></span><span class="token keyword" style="color:#00009f">var</span><span class="token plain"> </span><span class="token function-variable function" style="color:#d73a49">height</span><span class="token plain"> </span><span class="token operator" style="color:#393A34">=</span><span class="token plain"> </span><span class="token keyword" style="color:#00009f">function</span><span class="token plain"> </span><span class="token punctuation" style="color:#393A34">(</span><span class="token parameter">root</span><span class="token punctuation" style="color:#393A34">)</span><span class="token plain"> </span><span class="token punctuation" style="color:#393A34">{</span><span class="token plain"></span><br></span><span class="token-line" style="color:#393A34"><span class="token plain"> </span><span class="token keyword control-flow" style="color:#00009f">if</span><span class="token plain"> </span><span class="token punctuation" style="color:#393A34">(</span><span class="token plain">root </span><span class="token operator" style="color:#393A34">==</span><span class="token plain"> </span><span class="token keyword null nil" style="color:#00009f">null</span><span class="token punctuation" style="color:#393A34">)</span><span class="token plain"> </span><span class="token punctuation" style="color:#393A34">{</span><span class="token plain"></span><br></span><span class="token-line" style="color:#393A34"><span class="token plain"> </span><span class="token keyword control-flow" style="color:#00009f">return</span><span class="token plain"> </span><span class="token number" style="color:#36acaa">0</span><span class="token punctuation" style="color:#393A34">;</span><span class="token plain"></span><br></span><span class="token-line" style="color:#393A34"><span class="token plain"> </span><span class="token punctuation" style="color:#393A34">}</span><span class="token plain"></span><br></span><span class="token-line" style="color:#393A34"><span class="token plain" style="display:inline-block"></span><br></span><span class="token-line" style="color:#393A34"><span class="token plain"> </span><span class="token keyword" style="color:#00009f">const</span><span class="token plain"> left </span><span class="token operator" style="color:#393A34">=</span><span class="token plain"> </span><span class="token function" style="color:#d73a49">height</span><span class="token punctuation" style="color:#393A34">(</span><span class="token plain">root</span><span class="token punctuation" style="color:#393A34">.</span><span class="token property-access">left</span><span class="token punctuation" style="color:#393A34">)</span><span class="token punctuation" style="color:#393A34">;</span><span class="token plain"></span><br></span><span class="token-line" style="color:#393A34"><span class="token plain"> </span><span class="token keyword" style="color:#00009f">const</span><span class="token plain"> right </span><span class="token operator" style="color:#393A34">=</span><span class="token plain"> </span><span class="token function" style="color:#d73a49">height</span><span class="token punctuation" style="color:#393A34">(</span><span class="token plain">root</span><span class="token punctuation" style="color:#393A34">.</span><span class="token property-access">right</span><span class="token punctuation" style="color:#393A34">)</span><span class="token punctuation" style="color:#393A34">;</span><span class="token plain"></span><br></span><span class="token-line" style="color:#393A34"><span class="token plain" style="display:inline-block"></span><br></span><span class="token-line" style="color:#393A34"><span class="token plain"> </span><span class="token keyword control-flow" style="color:#00009f">if</span><span class="token plain"> </span><span class="token punctuation" style="color:#393A34">(</span><span class="token plain">left </span><span class="token operator" style="color:#393A34">===</span><span class="token plain"> </span><span class="token operator" style="color:#393A34">-</span><span class="token number" style="color:#36acaa">1</span><span class="token plain"> </span><span class="token operator" style="color:#393A34">||</span><span class="token plain"> right </span><span class="token operator" style="color:#393A34">===</span><span class="token plain"> </span><span class="token operator" style="color:#393A34">-</span><span class="token number" style="color:#36acaa">1</span><span class="token plain"> </span><span class="token operator" style="color:#393A34">||</span><span class="token plain"> </span><span class="token known-class-name class-name">Math</span><span class="token punctuation" style="color:#393A34">.</span><span class="token method function property-access" style="color:#d73a49">abs</span><span class="token punctuation" style="color:#393A34">(</span><span class="token plain">left </span><span class="token operator" style="color:#393A34">-</span><span class="token plain"> right</span><span class="token punctuation" style="color:#393A34">)</span><span class="token plain"> </span><span class="token operator" style="color:#393A34">></span><span class="token plain"> </span><span class="token number" style="color:#36acaa">1</span><span class="token punctuation" style="color:#393A34">)</span><span class="token plain"> </span><span class="token punctuation" style="color:#393A34">{</span><span class="token plain"></span><br></span><span class="token-line" style="color:#393A34"><span class="token plain"> </span><span class="token keyword control-flow" style="color:#00009f">return</span><span class="token plain"> </span><span class="token operator" style="color:#393A34">-</span><span class="token number" style="color:#36acaa">1</span><span class="token punctuation" style="color:#393A34">;</span><span class="token plain"></span><br></span><span class="token-line" style="color:#393A34"><span class="token plain"> </span><span class="token punctuation" style="color:#393A34">}</span><span class="token plain"></span><br></span><span class="token-line" style="color:#393A34"><span class="token plain" style="display:inline-block"></span><br></span><span class="token-line" style="color:#393A34"><span class="token plain"> </span><span class="token keyword control-flow" style="color:#00009f">return</span><span class="token plain"> </span><span class="token known-class-name class-name">Math</span><span class="token punctuation" style="color:#393A34">.</span><span class="token method function property-access" style="color:#d73a49">max</span><span class="token punctuation" style="color:#393A34">(</span><span class="token plain">left</span><span class="token punctuation" style="color:#393A34">,</span><span class="token plain"> right</span><span class="token punctuation" style="color:#393A34">)</span><span class="token plain"> </span><span class="token operator" style="color:#393A34">+</span><span class="token plain"> </span><span class="token number" style="color:#36acaa">1</span><span class="token punctuation" style="color:#393A34">;</span><span class="token plain"></span><br></span><span class="token-line" style="color:#393A34"><span class="token plain"></span><span class="token punctuation" style="color:#393A34">}</span><span class="token punctuation" style="color:#393A34">;</span><br></span></code></pre><div class="buttonGroup__atx"><button type="button" aria-label="Copy code to clipboard" title="Copy" class="clean-btn"><span class="copyButtonIcons_eSgA" aria-hidden="true"><svg class="copyButtonIcon_y97N" viewBox="0 0 24 24"><path d="M19,21H8V7H19M19,5H8A2,2 0 0,0 6,7V21A2,2 0 0,0 8,23H19A2,2 0 0,0 21,21V7A2,2 0 0,0 19,5M16,1H4A2,2 0 0,0 2,3V17H4V3H16V1Z"></path></svg><svg class="copyButtonSuccessIcon_LjdS" viewBox="0 0 24 24"><path d="M21,7L9,19L3.5,13.5L4.91,12.09L9,16.17L19.59,5.59L21,7Z"></path></svg></span></button></div></div></div><h4 class="anchor anchorWithHideOnScrollNavbar_WYt5" id="时间复杂度分析-1">时间复杂度分析<a href="#时间复杂度分析-1" class="hash-link" aria-label="Direct link to 时间复杂度分析" title="Direct link to 时间复杂度分析"></a></h4><p>由于是后序遍历,每个节点只会被调用 1 次,所以,该方法的时间复杂度是 O(n)。</p><h4 class="anchor anchorWithHideOnScrollNavbar_WYt5" id="空间复杂度分析-1">空间复杂度分析<a href="#空间复杂度分析-1" class="hash-link" aria-label="Direct link to 空间复杂度分析" title="Direct link to 空间复杂度分析"></a></h4><p>空间复杂度取决于递归调用的层数,不会超过 n 层,所以空间复杂度是 O(n)。</p></div></article><nav class="pagination-nav docusaurus-mt-lg" aria-label="Docs pages navigation"><a class="pagination-nav__link pagination-nav__link--prev" href="/awesome-interview/book1/coding-promise"><div class="pagination-nav__sublabel">Previous</div><div class="pagination-nav__label">编码:实现一个符合 Promises/A+ 规范的 Promise</div></a><a class="pagination-nav__link pagination-nav__link--next" href="/awesome-interview/book1/topic-enter-url-display-xx"><div class="pagination-nav__sublabel">Next</div><div class="pagination-nav__label">综合:浏览器从输入网址到页面展现的过程</div></a></nav></div></div><div class="col col--3"><div class="tableOfContents_bqdL thin-scrollbar theme-doc-toc-desktop"><ul class="table-of-contents table-of-contents__left-border"><li><a href="#题目描述" class="table-of-contents__link toc-highlight">题目描述</a></li><li><a href="#基本知识点" class="table-of-contents__link toc-highlight">基本知识点</a></li><li><a href="#题解" class="table-of-contents__link toc-highlight">题解</a><ul><li><a href="#解法一" class="table-of-contents__link toc-highlight">解法一</a><ul><li><a href="#思路" class="table-of-contents__link toc-highlight">思路</a></li><li><a href="#代码" class="table-of-contents__link toc-highlight">代码</a></li><li><a href="#时间复杂度分析" class="table-of-contents__link toc-highlight">时间复杂度分析</a></li><li><a href="#空间复杂度分析" class="table-of-contents__link toc-highlight">空间复杂度分析</a></li></ul></li><li><a href="#解法二" class="table-of-contents__link toc-highlight">解法二</a><ul><li><a href="#思路-1" class="table-of-contents__link toc-highlight">思路</a></li><li><a href="#代码-1" class="table-of-contents__link toc-highlight">代码</a></li><li><a href="#时间复杂度分析-1" class="table-of-contents__link toc-highlight">时间复杂度分析</a></li><li><a href="#空间复杂度分析-1" class="table-of-contents__link toc-highlight">空间复杂度分析</a></li></ul></li></ul></li></ul></div></div></div><div class="row"><div class="col"><div class="react-utterences"><div>Loading script...</div></div></div><div class="col col--3"></div></div></div></main></div></div></div>
|
||
<script src="/awesome-interview/assets/js/runtime~main.a75952d5.js"></script>
|
||
<script src="/awesome-interview/assets/js/main.a5e14537.js"></script>
|
||
</body>
|
||
</html> |