Use JS to implement the establishment of a binary search tree and some traversal methods

//以下定义一个节点类 function Node(data,left,right){ // 节点的键值 this.data = data; // 左节点 this.left = left; // 右节点 this.right = left; // 显示该节点的键值 this.show = show; } // 实现show方法 function show(){ return this.data; }

// 二叉查找树BST // 有一个节点属性，还有一些其他的方法，以下定义一个二叉查找树BST类 function BST(){ // 根节点初始化为空 this.root = null; // 方法 // 插入 this.insert = insert; // Use JS to implement the establishment of a binary search tree and some traversal methods this.inorder = inorder; // Use JS to implement the establishment of a binary search tree and some traversal methods this.preorder = preorder; // Use JS to implement the establishment of a binary search tree and some traversal methods this.postorder = postorder; } //实现insert插入方法 function insert(data){ // 创建一个节点保存数据 var node = new Node(data,null,null); // 下面将节点node插入到树中 // 如果树是空的，就将节点设为根节点 if(!this.root){ this.root = node; }else{ //树不为空 // 判断插在父节点的左边还是右边 // 所以先要保存一下父节点 // var parent = this.root; var current = this.root; var parent; // 如果要插入的节点键值小于父节点键值，则插在父节点左边， // 前提是父节点的左边为空，否则要将父节点往下移一层， // 然后再做判断 while(true){ // data小于父节点的键值 parent = current; if(data < parent.data){ // 将父节点往左下移(插入左边) // parent = parent.left; current = current.left; // 如果节点为空，则直接插入 if(!current){ // ！！！此处特别注意，如果就这样把parent赋值为node，也仅仅只是parent指向node， // 而并没有加到父元素的左边！！！根本没有加到树中去。所以要先记住父元素，再把当前元素加入进去 parent.left = node; break; } }else{ // 将父节点往右下移(插入右边) current = current.right; if(!current){ parent.right = node; break; } } } } } //实现inorder遍历方法(左中右) function inorder(node){ if(node){ inorder(node.left); console.log(node.show()); inorder(node.right); } } // Use JS to implement the establishment of a binary search tree and some traversal methods(中左右) function preorder(node){ if(node){ console.log(node.show()); preorder(node.left); preorder(node.right); } } // Use JS to implement the establishment of a binary search tree and some traversal methods(左右中) function postorder(node){ if(node){ preorder(node.left); preorder(node.right); console.log(node.show()); } }

// Use JS to implement the establishment of a binary search tree and some traversal methods(左右中) function postorder(node){ if(node){ postorder(node.left); postorder(node.right); console.log(node.show()); } } // 实例化一个BST树 var tree = new BST(); // 添加节点 tree.insert(30); tree.insert(14); tree.insert(35); tree.insert(12); tree.insert(17); // Use JS to implement the establishment of a binary search tree and some traversal methods tree.inorder(tree.root); // Use JS to implement the establishment of a binary search tree and some traversal methods tree.preorder(tree.root); // Use JS to implement the establishment of a binary search tree and some traversal methods tree.postorder(tree.root);