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Merge pull request krahets#174 from justin-tse/dev-js-hash
Add the JavaScript code and docs for Chapter of Hash Map
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‎codes/javascript/chapter_hashing/array_hash_map.js

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/*
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* File: array_hash_map.js
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* Created Time: 2022-12-26
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* Author: Justin ([email protected])
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*/
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/* 键值对 Number -> String */
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class Entry {
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constructor(key, val) {
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this.key = key;
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this.val = val;
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}
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}
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/* 基于数组简易实现的哈希表 */
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class ArrayHashMap {
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#bucket;
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constructor() {
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// 初始化一个长度为 100 的桶（数组）
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this.#bucket = new Array(100).fill(null);
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}
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/* 哈希函数 */
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#hashFunc(key) {
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return key % 100;
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}
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/* 查询操作 */
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get(key) {
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let index = this.#hashFunc(key);
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let entry = this.#bucket[index];
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if (entry === null) return null;
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return entry.val;
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}
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/* 添加操作 */
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set(key, val) {
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let index = this.#hashFunc(key);
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this.#bucket[index] = new Entry(key, val);
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}
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/* 删除操作 */
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delete(key) {
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let index = this.#hashFunc(key);
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// 置为 null ，代表删除
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this.#bucket[index] = null;
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}
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/* 获取所有键值对 */
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entries() {
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let arr = [];
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for (let i = 0; i < this.#bucket.length; i++) {
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if (this.#bucket[i]) {
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arr.push(this.#bucket[i]);
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}
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}
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return arr;
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}
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/* 获取所有键 */
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keys() {
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let arr = [];
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for (let i = 0; i < this.#bucket.length; i++) {
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if (this.#bucket[i]) {
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arr.push(this.#bucket[i]?.key);
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}
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}
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return arr;
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}
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/* 获取所有值 */
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values() {
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let arr = [];
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for (let i = 0; i < this.#bucket.length; i++) {
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if (this.#bucket[i]) {
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arr.push(this.#bucket[i]?.val);
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}
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}
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return arr;
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}
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/* 打印哈希表 */
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print() {
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let entrySet = this.entries();
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for (const entry of entrySet) {
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if (!entry) continue;
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console.info(`${entry.key} -> ${entry.val}`);
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}
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}
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}
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/* Driver Code */
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/* 初始化哈希表 */
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const map = new ArrayHashMap();
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/* 添加操作 */
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// 在哈希表中添加键值对 (key, value)
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map.set(12836, '小哈');
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map.set(15937, '小啰');
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map.set(16750, '小算');
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map.set(13276, '小法');
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map.set(10583, '小鸭');
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console.info('\n添加完成后，哈希表为\nKey -> Value');
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map.print();
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/* 查询操作 */
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// 向哈希表输入键 key ，得到值 value
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let name = map.get(15937);
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console.info('\n输入学号 15937 ，查询到姓名 ' + name);
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/* 删除操作 */
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// 在哈希表中删除键值对 (key, value)
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map.delete(10583);
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console.info('\n删除 10583 后，哈希表为\nKey -> Value');
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map.print();
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/* 遍历哈希表 */
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console.info('\n遍历键值对 Key->Value');
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for (const entry of map.entries()) {
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if (!entry) continue;
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console.info(entry.key + ' -> ' + entry.val);
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}
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console.info('\n单独遍历键 Key');
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for (const key of map.keys()) {
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console.info(key);
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}
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console.info('\n单独遍历值 Value');
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for (const val of map.values()) {
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console.info(val);
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}

‎codes/javascript/chapter_hashing/hash_map.js

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/*
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* File: hash_map.js
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* Created Time: 2022-12-26
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* Author: Justin ([email protected])
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*/
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/* Driver Code */
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/* 初始化哈希表 */
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const map = new Map();
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/* 添加操作 */
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// 在哈希表中添加键值对 (key, value)
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map.set(12836, '小哈');
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map.set(15937, '小啰');
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map.set(16750, '小算');
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map.set(13276, '小法');
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map.set(10583, '小鸭');
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console.info('\n添加完成后，哈希表为\nKey -> Value');
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console.info(map);
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/* 查询操作 */
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// 向哈希表输入键 key ，得到值 value
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let name = map.get(15937);
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console.info('\n输入学号 15937 ，查询到姓名 ' + name);
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/* 删除操作 */
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// 在哈希表中删除键值对 (key, value)
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map.delete(10583);
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console.info('\n删除 10583 后，哈希表为\nKey -> Value');
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console.info(map);
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/* 遍历哈希表 */
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console.info('\n遍历键值对 Key->Value');
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for (const [k, v] of map.entries()) {
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console.info(k + ' -> ' + v);
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}
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console.info('\n单独遍历键 Key');
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for (const k of map.keys()) {
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console.info(k);
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}
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console.info('\n单独遍历值 Value');
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for (const v of map.values()) {
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console.info(v);
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}

‎docs/chapter_hashing/hash_map.md

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=== "JavaScript"
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```js title="hash_map.js"
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/* 初始化哈希表 */
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const map = new ArrayHashMap();
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/* 添加操作 */
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// 在哈希表中添加键值对 (key, value)
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map.set(12836, '小哈');
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map.set(15937, '小啰');
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map.set(16750, '小算');
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map.set(13276, '小法');
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map.set(10583, '小鸭');
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/* 查询操作 */
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// 向哈希表输入键 key ，得到值 value
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let name = map.get(15937);
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/* 删除操作 */
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// 在哈希表中删除键值对 (key, value)
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map.delete(10583);
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```
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=== "TypeScript"
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=== "JavaScript"
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```js title="hash_map.js"
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/* 遍历哈希表 */
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// 遍历键值对 key->value
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for (const entry of map.entries()) {
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if (!entry) continue;
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console.info(entry.key + ' -> ' + entry.val);
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}
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// 单独遍历键 key
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for (const key of map.keys()) {
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console.info(key);
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}
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// 单独遍历值 value
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for (const val of map.values()) {
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console.info(val);
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}
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```
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=== "TypeScript"
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=== "JavaScript"
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```js title="array_hash_map.js"
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/* 键值对 Number -> String */
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class Entry {
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constructor(key, val) {
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this.key = key;
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this.val = val;
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}
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}
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/* 基于数组简易实现的哈希表 */
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class ArrayHashMap {
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#bucket;
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constructor() {
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// 初始化一个长度为 100 的桶（数组）
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this.#bucket = new Array(100).fill(null);
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}
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/* 哈希函数 */
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#hashFunc(key) {
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return key % 100;
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}
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/* 查询操作 */
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get(key) {
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let index = this.#hashFunc(key);
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let entry = this.#bucket[index];
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if (entry === null) return null;
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return entry.val;
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}
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/* 添加操作 */
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set(key, val) {
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let index = this.#hashFunc(key);
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this.#bucket[index] = new Entry(key, val);
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}
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/* 删除操作 */
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delete(key) {
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let index = this.#hashFunc(key);
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// 置为 null ，代表删除
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this.#bucket[index] = null;
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}
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}
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```
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=== "TypeScript"

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