B+树算法javascript
时间: 2023-06-22 14:41:28 浏览: 46
下面是一个简单的B+树算法javascript实现:
```javascript
class BPlusTreeNode {
constructor(order, isLeaf = false) {
this.order = order;
this.isLeaf = isLeaf;
this.keys = [];
this.children = [];
this.next = null;
}
isFull() {
return this.keys.length === this.order;
}
split() {
const mid = Math.ceil(this.order / 2) - 1;
const left = new BPlusTreeNode(this.order, this.isLeaf);
const right = new BPlusTreeNode(this.order, this.isLeaf);
left.keys = this.keys.slice(0, mid);
right.keys = this.keys.slice(mid);
if (this.isLeaf) {
left.next = right;
left.children = this.children.slice(0, mid);
right.children = this.children.slice(mid);
} else {
left.children = this.children.slice(0, mid + 1);
right.children = this.children.slice(mid + 1);
}
return { left, right, median: this.keys[mid] };
}
}
class BPlusTree {
constructor(order) {
this.order = order;
this.root = new BPlusTreeNode(order, true);
}
insert(key, value) {
let node = this.root;
if (node.isFull()) {
this.root = new BPlusTreeNode(this.order);
this.root.children.push(node);
const { left, right, median } = node.split();
this.root.keys.push(median);
this.root.children[0] = left;
this.root.children[1] = right;
node = key > median ? right : left;
}
let parent;
while (!node.isLeaf) {
parent = node;
node = key > parent.keys[parent.keys.length - 1] ? parent.children[parent.keys.length] : parent.children.find((child, index) => key < parent.keys[index]);
if (node.isFull()) {
const { left, right, median } = node.split();
parent.children[parent.children.indexOf(node)] = left;
parent.children.splice(parent.children.indexOf(left) + 1, 0, right);
parent.keys.splice(parent.children.indexOf(left), 0, median);
node = key > median ? right : left;
}
}
node.keys.push(key);
node.children.push(value);
}
search(key) {
let node = this.root;
while (!node.isLeaf) {
node = node.children.find((child, index) => key <= node.keys[index]);
}
return node.children[node.keys.indexOf(key)];
}
}
```
这个实现使用了两个类,一个是BPlusTreeNode表示B+树的节点,一个是BPlusTree表示整个B+树。在BPlusTreeNode类中实现了分裂节点、判断节点是否已满、获取节点的中间值等方法。在BPlusTree类中实现了插入和查找操作。