二叉树和二叉查找树

树的定义

树由一组以边连接的节点组成

数的相关概念

1. 路径：一个节点到另一个节点的一组边
   
2. 遍历：以某种特定顺序访问树中所有节点

3. 深度：树的层数

   实现二叉查找树

   //构建Node对象
   function Node(data, left, right) {
       this.data = data;
       this.left = left;
       this.right = right;
       this.show = show;
   }
   
   function show() {
       return this.data;
   }
   //实现二叉查找树
   function BST() {
       this.root = null;
       this.insert = insert;
       this.inOrder = inOrder;
       this.preOrder = preOrder;
       this.postOrder = postOrder;
       this.getMin = getMin;
       this.getMax = getMax;
       this.find = find;
   }
   //插入节点
   function insert(data) {
       var n = new Node(data, null, null);
       if(this.root == null) {
           this.root = n;
       }
       else {
           var curr = this.root;
           var parent;
           while(true) {
               parent = curr;
               if(data < curr.data) {
                   curr = curr.left;
                   if(curr == null) {
                       parent.left = n;
                       break;
                   }
               }
               else {
                   curr = curr.right;
                   if(curr == null) {
                       parent.right = n;
                       break;
                   }
               }
           }
       }
   }
   //中序遍历
   function inOrder(node) {
       if(!(node == null)) {
           inOrder(node.left);
           console.log(node.show() + " ");
           inOrder(node.right);
       }
   }
   //先序遍历
   function preOrder(node) {
       if(!(node == null)) {
           console.log(node.show() + " ");
           preOrder(node.left);
           preOrder(node.right);
       }
   }
   //后序遍历
   function postOrder(node) {
       if(!(node == null)) {
           postOrder(node.left);
           postOrder(node.right);
           console.log(node.show() + " ");
       }
   }
   //查找最小值
   function getMin() {
       var curr = this.root;
       while(!(curr.left == null)) {
           curr = curr.left;
       }
       return curr.data;
   }
   //查找最大值
   function getMax() {
       var curr = this.root;
       while(!(curr.right == null)) {
           curr = curr.right;
       }
       return curr.data;
   }
   //查找任意值
   function find(data) {
       var curr = this.root;
       while(curr != null) {
           if(curr.data == data) {
               return curr;
           }
           else if(data < curr.data) {
               curr = curr.left;
           }
           else {
               curr = curr.right;
           }
       }
       return null;
   }