134 lines
3.4 KiB
JavaScript
134 lines
3.4 KiB
JavaScript
/**
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* author dreamapplehappy
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* 关于代码的一些解释可以看一下这里：https://github.com/dreamapplehappy/blog/tree/master/2018/12/02
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*/
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const MAX_LEVEL = 16;
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class Node {
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constructor({
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data = -1,
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maxLevel = 0,
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refer = new Array(MAX_LEVEL)
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} = {}) {
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this.data = data;
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this.maxLevel = maxLevel;
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this.refer = refer
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}
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}
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class SkipList{
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constructor() {
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this.head = new Node();
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this.levelCount = 1;
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}
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randomLevel() {
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let level = 1;
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for (let i = 1; i < MAX_LEVEL; i++) {
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if (Math.random() < 0.5) {
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level++;
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}
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}
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return level;
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}
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insert(value) {
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const level = this.randomLevel();
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const newNode = new Node();
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newNode.data = value;
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newNode.maxLevel = level;
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const update = new Array(level).fill(new Node());
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let p = this.head;
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for(let i = level - 1; i >= 0; i--) {
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while(p.refer[i] !== undefined && p.refer[i].data < value) {
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p = p.refer[i];
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}
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update[i] = p;
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}
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for(let i = 0; i < level; i++) {
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newNode.refer[i] = update[i].refer[i];
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update[i].refer[i] = newNode;
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}
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if(this.levelCount < level) {
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this.levelCount = level;
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}
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}
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find(value) {
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if(!value){return null}
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let p = this.head;
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for(let i = this.levelCount - 1; i >= 0; i--) {
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while(p.refer[i] !== undefined && p.refer[i].data < value) {
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p = p.refer[i];
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}
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}
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if(p.refer[0] !== undefined && p.refer[0].data === value) {
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return p.refer[0];
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}
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return null;
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}
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remove(value) {
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let _node;
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let p = this.head;
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const update = new Array(new Node());
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for(let i = this.levelCount - 1; i >= 0; i--) {
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while(p.refer[i] !== undefined && p.refer[i].data < value){
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p = p.refer[i];
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}
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update[i] = p;
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}
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if(p.refer[0] !== undefined && p.refer[0].data === value) {
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_node = p.refer[0];
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for(let i = 0; i <= this.levelCount - 1; i++) {
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if(update[i].refer[i] !== undefined && update[i].refer[i].data === value) {
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update[i].refer[i] = update[i].refer[i].refer[i];
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}
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}
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return _node;
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}
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return null;
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}
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printAll() {
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let p = this.head;
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while(p.refer[0] !== undefined) {
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console.log(p.refer[0].data)
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p = p.refer[0];
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}
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}
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}
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test();
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function test() {
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let list = new SkipList();
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let length = 20000;
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//顺序插入
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for (let i = 1; i <= 10; i++) {
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list.insert(i);
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}
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//输出一次
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list.printAll();
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console.time('create length-10')
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//插入剩下的
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for (let i = 11; i <= length - 10; i++) {
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list.insert(i);
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}
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console.timeEnd('create length-10')
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//搜索 10次
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for (let j = 0; j < 10; j++) {
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let key = Math.floor(Math.random() * length + 1);
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console.log(key, list.find(key))
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}
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//搜索不存在的值
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console.log('null:', list.find(length + 1));
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//搜索5000次统计时间
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console.time('search 5000');
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for (let j = 0; j < 5000; j++) {
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let key = Math.floor(Math.random() * length + 1);
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}
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console.timeEnd('search 5000');
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}
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