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https://github.com/krahets/hello-algo.git
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e720aa2d24
* Sync recent changes to the revised Word. * Revised the preface chapter * Revised the introduction chapter * Revised the computation complexity chapter * Revised the chapter data structure * Revised the chapter array and linked list * Revised the chapter stack and queue * Revised the chapter hashing * Revised the chapter tree * Revised the chapter heap * Revised the chapter graph * Revised the chapter searching * Reivised the sorting chapter * Revised the divide and conquer chapter * Revised the chapter backtacking * Revised the DP chapter * Revised the greedy chapter * Revised the appendix chapter * Revised the preface chapter doubly * Revised the figures
147 lines
3.3 KiB
JavaScript
147 lines
3.3 KiB
JavaScript
/**
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* File: array_binary_tree.js
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* Created Time: 2023-08-06
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* Author: yuan0221 (yl1452491917@gmail.com)
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*/
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const { arrToTree } = require('../modules/TreeNode');
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const { printTree } = require('../modules/PrintUtil');
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/* 数组表示下的二叉树类 */
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class ArrayBinaryTree {
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#tree;
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/* 构造方法 */
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constructor(arr) {
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this.#tree = arr;
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}
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/* 节点数量 */
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size() {
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return this.#tree.length;
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}
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/* 获取索引为 i 节点的值 */
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val(i) {
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// 若索引越界，则返回 null ，代表空位
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if (i < 0 || i >= this.size()) return null;
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return this.#tree[i];
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}
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/* 获取索引为 i 节点的左子节点的索引 */
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left(i) {
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return 2 * i + 1;
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}
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/* 获取索引为 i 节点的右子节点的索引 */
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right(i) {
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return 2 * i + 2;
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}
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/* 获取索引为 i 节点的父节点的索引 */
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parent(i) {
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return Math.floor((i - 1) / 2); // 向下整除
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}
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/* 层序遍历 */
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levelOrder() {
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let res = [];
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// 直接遍历数组
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for (let i = 0; i < this.size(); i++) {
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if (this.val(i) !== null) res.push(this.val(i));
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}
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return res;
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}
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/* 深度优先遍历 */
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#dfs(i, order, res) {
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// 若为空位，则返回
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if (this.val(i) === null) return;
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// 前序遍历
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if (order === 'pre') res.push(this.val(i));
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this.#dfs(this.left(i), order, res);
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// 中序遍历
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if (order === 'in') res.push(this.val(i));
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this.#dfs(this.right(i), order, res);
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// 后序遍历
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if (order === 'post') res.push(this.val(i));
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}
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/* 前序遍历 */
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preOrder() {
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const res = [];
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this.#dfs(0, 'pre', res);
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return res;
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}
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/* 中序遍历 */
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inOrder() {
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const res = [];
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this.#dfs(0, 'in', res);
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return res;
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}
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/* 后序遍历 */
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postOrder() {
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const res = [];
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this.#dfs(0, 'post', res);
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return res;
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}
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}
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/* Driver Code */
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// 初始化二叉树
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// 这里借助了一个从数组直接生成二叉树的函数
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const arr = Array.of(
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1,
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2,
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3,
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4,
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null,
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6,
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7,
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8,
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9,
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null,
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null,
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12,
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null,
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null,
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15
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);
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const root = arrToTree(arr);
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console.log('\n初始化二叉树\n');
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console.log('二叉树的数组表示：');
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console.log(arr);
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console.log('二叉树的链表表示：');
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printTree(root);
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// 数组表示下的二叉树类
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const abt = new ArrayBinaryTree(arr);
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// 访问节点
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const i = 1;
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const l = abt.left(i);
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const r = abt.right(i);
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const p = abt.parent(i);
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console.log('\n当前节点的索引为 ' + i + ' ，值为 ' + abt.val(i));
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console.log(
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'其左子节点的索引为 ' + l + ' ，值为 ' + (l === null ? 'null' : abt.val(l))
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);
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console.log(
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'其右子节点的索引为 ' + r + ' ，值为 ' + (r === null ? 'null' : abt.val(r))
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);
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console.log(
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'其父节点的索引为 ' + p + ' ，值为 ' + (p === null ? 'null' : abt.val(p))
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);
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// 遍历树
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let res = abt.levelOrder();
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console.log('\n层序遍历为：' + res);
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res = abt.preOrder();
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console.log('前序遍历为：' + res);
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res = abt.inOrder();
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console.log('中序遍历为：' + res);
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res = abt.postOrder();
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console.log('后序遍历为：' + res);
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