文章来源https://www.nczonline.net/blog/2009/06/09/computer-science-in-javascript-binary-search-tree-part-1/

基本界面

function BinarySearchTree() { this._root = null; } BinarySearchTree.prototype = //restore constructor constructor: BinarySearchTree, add: function (value){ }, contains: function(value){ }, remove: function(value){ }, size: function(){ }, toArray: function(){ }, toString: function(){ } };//这里size,toArray,toString是文章作者添加的新函数

contians

BinarySearchTree.prototype = { //more code contains: function(value){ var found = false, current = this._root //make sure there's a node to search while(!found && current){ //if the value is less than the current node's, go left if (value < current.value){ current = current.left; //if the value is greater than the current node's, go right } else if (value > current.value){ current = current.right; //values are equal, found it! } else { found = true; } } //only proceed if the node was found return found; }, //more code };

add

`BinarySearchTree.prototype = {
//more code
add: function(value){
//create a new item object, place data in
var node = {
value: value,

            left: null,
            right: null
        },
        //used to traverse the structure
        current;
    //special case: no items in the tree yet
    if (this._root === null){
        this._root = node;
    } else {
        current = this._root;
        while(true){
            //if the new value is less than this node's value, go left
            if (value < current.value){
                //if there's no left, then the new node belongs there
                if (current.left === null){
                    current.left = node;
                    break;
                } else {
                    current = current.left;
                }
            //if the new value is greater than this node's value, go right
            } else if (value > current.value){
                //if there's no right, then the new node belongs there
                if (current.right === null){
                    current.right = node;
                    break;
                } else {
                    current = current.right;
                }       
            //if the new value is equal to the current one, just ignore
            } else {
                break;
            }
        }
    }
},
//more code

};`

traverse遍历递归

BinarySearchTree.prototype = { //more code traverse: function(process){ //helper function function inOrder(node){ if (node){ //traverse the left subtree if (node.left !== null){ inOrder(node.left); } //call the process method on this node process.call(this, node); //traverse the right subtree if (node.right !== null){ inOrder(node.right); } } } //start with the root inOrder(this._root); }, //more code };

size/toArray/toString

BinarySearchTree.prototype = { //more code size: function(){ var length = 0; this.traverse(function(node){ length++; }); return length; }, toArray: function(){ var result = []; this.traverse(function(node){ result.push(node.value); }); return result; }, toString: function(){ return this.toArray().toString(); }, //more code };