二叉树

function BinaryTreed() {
    let Node = function (key) {
        this.key = key;
        this.left = null;
        this.right = null;
    }

    let root = null;
    let inserNode = function (node, newNode) {
        if (newNode.key < node.key) {
            if (node.left === null) {
                node.left = newNode
            } else {
                inserNode(node.left, newNode)
            }
        } else {
            if (node.right === null) {
                node.right = newNode
            } else {
                inserNode(node.right, newNode);
            }
        }
    }
    this.insert = function (key) {
        let node = new Node(key);
        if (root === null) {
            root = node;
        } else {
            inserNode(root, node);
        }
    }
}