|
| 1 | +/** |
| 2 | + * author dreamapplehappy |
| 3 | + * 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 |
| 4 | + */ |
| 5 | + |
| 6 | +const MAX_LEVEL = 16; |
| 7 | + |
| 8 | +class Node{ |
| 9 | + data = -1; |
| 10 | + maxLevel = 0; |
| 11 | + refer = new Array(MAX_LEVEL); |
| 12 | +} |
| 13 | + |
| 14 | +class SkipList{ |
| 15 | + levelCount = 1; |
| 16 | + head = new Node(); |
| 17 | + |
| 18 | + static randomLevel() { |
| 19 | + let level = 1; |
| 20 | + for(let i = 1; i < MAX_LEVEL; i++) { |
| 21 | + if(Math.random() < 0.5) { |
| 22 | + level++; |
| 23 | + } |
| 24 | + } |
| 25 | + return level; |
| 26 | + } |
| 27 | + |
| 28 | + insert(value) { |
| 29 | + const level = SkipList.randomLevel(); |
| 30 | + const newNode = new Node(); |
| 31 | + newNode.data = value; |
| 32 | + newNode.maxLevel = level; |
| 33 | + const update = new Array(level).fill(new Node()); |
| 34 | + let p = this.head; |
| 35 | + for(let i = level - 1; i >= 0; i--) { |
| 36 | + while(p.refer[i] !== undefined && p.refer[i].data < value) { |
| 37 | + p = p.refer[i]; |
| 38 | + } |
| 39 | + update[i] = p; |
| 40 | + } |
| 41 | + for(let i = 0; i < level; i++) { |
| 42 | + newNode.refer[i] = update[i].refer[i]; |
| 43 | + update[i].refer[i] = newNode; |
| 44 | + } |
| 45 | + if(this.levelCount < level) { |
| 46 | + this.levelCount = level; |
| 47 | + } |
| 48 | + } |
| 49 | + |
| 50 | + find(value) { |
| 51 | + if(!value){return null} |
| 52 | + let p = this.head; |
| 53 | + for(let i = this.levelCount - 1; i >= 0; i--) { |
| 54 | + while(p.refer[i] !== undefined && p.refer[i].data < value) { |
| 55 | + p = p.refer[i]; |
| 56 | + } |
| 57 | + } |
| 58 | + |
| 59 | + if(p.refer[0] !== undefined && p.refer[0].data === value) { |
| 60 | + return p.refer[0]; |
| 61 | + } |
| 62 | + return null; |
| 63 | + } |
| 64 | + |
| 65 | + remove(value) { |
| 66 | + let _node; |
| 67 | + let p = this.head; |
| 68 | + const update = new Array(new Node()); |
| 69 | + for(let i = this.levelCount - 1; i >= 0; i--) { |
| 70 | + while(p.refer[i] !== undefined && p.refer[i].data < value){ |
| 71 | + p = p.refer[i]; |
| 72 | + } |
| 73 | + update[i] = p; |
| 74 | + } |
| 75 | + |
| 76 | + if(p.refer[0] !== undefined && p.refer[0].data === value) { |
| 77 | + _node = p.refer[0]; |
| 78 | + for(let i = 0; i <= this.levelCount - 1; i++) { |
| 79 | + if(update[i].refer[i] !== undefined && update[i].refer[i].data === value) { |
| 80 | + update[i].refer[i] = update[i].refer[i].refer[i]; |
| 81 | + } |
| 82 | + } |
| 83 | + return _node; |
| 84 | + } |
| 85 | + return null; |
| 86 | + } |
| 87 | + |
| 88 | + printAll() { |
| 89 | + let p = this.head; |
| 90 | + while(p.refer[0] !== undefined) { |
| 91 | + // console.log(p.refer[0].data) |
| 92 | + p = p.refer[0]; |
| 93 | + } |
| 94 | + } |
| 95 | +} |
0 commit comments