二叉树

借鉴：http://www.conardli.top/docs/dataStructure/

完全二叉树

class Node {
    constructor(data, left, right){
        this.data = data
        this.left = left
        this.right = right
    }

    show() {
        console.log(this.data)
    }
}

class Tree{
    constructor(){
        this.root = null
    }

    insert(data){
        let node = new Node(data, null, null)
        if(!this.root){
            this.root = node
            return
        }
        let current = this.root
        // console.log(JSON.stringify(current), 'current')
        while(current){
            if(current.data < data) {
                if(!current.right){
                    current.right = node
                    return
                }
                current = current.right
            }else{
                if(!current.left){
                    current.left = node
                    return
                }
                current = current.left
            }
        }
    }

    preOrder(node){
        if(node){
            node.show()
            this.preOrder(node.left)
            this.preOrder(node.right)
        }
    }

    middleOrder(node){
        if(node){
            this.middleOrder(node.left)
            node.show()
            this.middleOrder(node.right)
        }
    }

    lasterOrder(node){
        if(node){
            this.lasterOrder(node.left)
            this.lasterOrder(node.right)
            node.show()
        }
    }

    getDeep(node, deep = 0) {
        if(!node){
            return deep
        }
        deep ++ 
        let lDeep = this.getDeep(node.left, deep)
        let rDeep = this.getDeep(node.right, deep)
        return Math.max(lDeep, rDeep)
    }
}

var t = new Tree();
t.insert(3);
t.insert(8);
t.insert(1);
t.insert(2);
t.insert(10);
t.insert(5);
t.insert(6);

// console.log(t.preOrder(t.root))
// console.log(t.middleOrder(t.root))
// console.log(t.lasterOrder(t.root))
console.log(t.getDeep(t.root))

根据前序遍历和中序遍历的接口，推出二叉树

function reConstructBinaryTree(pre, vin) {
    if(pre.length === 0){
        return null;
    }
    if(pre.length === 1){
        return new Node(pre[0]);
    }
    const value = pre[0];
    const index = vin.indexOf(value);
    const vinLeft = vin.slice(0,index);
    const vinRight = vin.slice(index+1);
    const preLeft = pre.slice(1,index+1);
    const preRight = pre.slice(index+1);
    const node = new Node(value);
    node.left = reConstructBinaryTree(preLeft, vinLeft);
    node.right = reConstructBinaryTree(preRight, vinRight);
    return node;
}

var list = reConstructBinaryTree([1,2,4,7,3,5,6,8], [4,7,2,1,5,3,8,6])