二叉 DOM 树的遍历
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- function Tree() {
-
- var Node = function(key){
- this.key = key;
- this.left = null;
- this.right = null;
- }
-
- root =null;
- }
前序遍历
<code style="font-family: 'Source Code Pro', Consolas, Menlo, Monaco, 'Courier New', monospace; font-size: 1em; color: inherit; padding: 0px; white-space: inherit; background: none;">首先访问根结点,然后遍历左子树,最后遍历右子树</code>
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- Tree.prototype.preOrderTraverse = function(callback){
- preOrder(root, callback);
- }
- var preOrder = function(node,callback){
- if(node !== null){
- callback(node.key);
- preOrder(node.left, callback);
- preOrder(node.right, callback);
- }
- }
-
<code style="font-family: 'Source Code Pro', Consolas, Menlo, Monaco, 'Courier New', monospace; font-size: 1em; color: inherit; padding: 0px; white-space: inherit; background: none;">修改为DOM二叉树:</code>
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- var preOrder = function(node,callback) {
- callback(node);
- if(node.firstElementChild) {
- this.preOrder(node.firstElementChild,callback);
- }
- if(node.lastElementChild) {
- this.preOrder(node.lastElementChild,callback);
- }
- };
中序遍历
<code style="font-family: 'Source Code Pro', Consolas, Menlo, Monaco, 'Courier New', monospace; font-size: 1em; color: inherit; padding: 0px; white-space: inherit; background: none;">首先遍历左子树,然后访问根结点,最后遍历右子树。</code>
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- Tree.prototype.inOrderTraverse = function(callback){
- inOrder(root, callback);
- }
- var inOrder = function(node,callback){
- if(node !== null){
- inOrder(node.left,callback);
- callback(node.key);
- inOrder(node.right, calback);
- }
- }
<code style="font-family: 'Source Code Pro', Consolas, Menlo, Monaco, 'Courier New', monospace; font-size: 1em; color: inherit; padding: 0px; white-space: inherit; background: none;">修改为DOM二叉树:</code>
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- var inOrder = function(node,callback){
- if(node.firstElementChild) {
- this.inOrder(node.firstElementChild);
- }
- callback(node);
- if(node.lastElementChild) {
- this.inOrder(node.lastElementChild);
- }
- }
后序遍历
<code style="font-family: 'Source Code Pro', Consolas, Menlo, Monaco, 'Courier New', monospace; font-size: 1em; color: inherit; padding: 0px; white-space: inherit; background: none;">首先遍历左子树,然后遍历右子树,最后访问根结点。</code>
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- Tree.prototype.postOrderTraverse = function(callback){
- postOrder(root, callback);
- }
- var postOrder = function(node,callback){
- if(node !== null){
- postOrder(node.left,callback);
- postOrder(node.right, calback);
- callback(node.key);
-
- }
- }
<code style="font-family: 'Source Code Pro', Consolas, Menlo, Monaco, 'Courier New', monospace; font-size: 1em; color: inherit; padding: 0px; white-space: inherit; background: none;">修改为DOM二叉树:</code>
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- var postOrder = function(node,callback){
- if(node.firstElementChild) {
- this.postOrder(node.firstElementChild);
- }
- if(node.lastElementChild) {
- this.postOrder(node.lastElementChild);
- }
- callback(node);
- }
多叉 DOM 树的遍历
广度优先遍历
<code style="font-family: 'Source Code Pro', Consolas, Menlo, Monaco, 'Courier New', monospace; font-size: 1em; color: inherit; padding: 0px; white-space: inherit; background: none;">首先遍历根节点,然后访问第一层节点,第二层节点,....,直到访问到最后一层。</code>
<code style="font-family: 'Source Code Pro', Consolas, Menlo, Monaco, 'Courier New', monospace; font-size: 1em; color: inherit; padding: 0px; white-space: inherit; background: none;">借助于队列,用非递归的方式对多叉树进行遍历</code>
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- Tree.prototype.BFSearch = function(node,callback){
- var queue=[];
- while(node!=null){
- callback(node);
- if(node.children.length!=0){
- for (var i=0;i<node.children.length;i++){
- queue.push(node.children[i]);
- }
- }
- node=queue.shift();
- }
- };
深度优先遍历
<code style="font-family: 'Source Code Pro', Consolas, Menlo, Monaco, 'Courier New', monospace; font-size: 1em; color: inherit; padding: 0px; white-space: inherit; background: none;">首先遍历根节点,然后沿着一条路径遍历到最深的一层,最后在逐层返回。</code>
<code style="font-family: 'Source Code Pro', Consolas, Menlo, Monaco, 'Courier New', monospace; font-size: 1em; color: inherit; padding: 0px; white-space: inherit; background: none;">借助于栈,实现多叉 DOM树 的深度优先遍历。</code>
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- Tree.prototype.DFSearch = function(node,callback){
- var stack=[];
- while(node!=null){
- callback(node);
- if(node.children.length!=0){
- for (var i=node.children.length-1;i>=0;i--){
- stack.push(node.children[i]);
- }
- }
- node = stack.pop();
- }
- };
二叉 DOM 树的前序、中序、后序遍历,是深度优先遍历的特例
因此,参考深度优先遍历,借助栈,可以以非递归的方式,实现二叉 DOM 树的 前序、中序和后序遍历
非递归实现二叉 DOM 树的前序遍历
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- Tree.prototype.preOrder = function(node,callback) {
- var stack=[];
- while(node!== null || stack.length!=0){
- while(node!==null){
- stack.push(node);
- callback.push(node);
- node=node.firstElementChild;
- }
- node=stack.pop();
- node=node.lastElementChild;
- }
- };
非递归实现二叉 DOM 树的中序遍历
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- Tree.prototype.inOrder = function(node,callback) {
- var stack=[];
- while(node!== null || stack.length!=0){
- while(node!==null){
- stack.push(node);
- node=node.firstElementChild;
- }
- node=stack.pop();
- callback(node);
- node=node.lastElementChild;
- }
- };
非递归实现二叉 DOM 树的后序遍历
- 每个节点,都压入栈两次;
- 在循环体中,每次弹出一个节点赋给node
- 如果node仍然等于栈的头结点,说明node的孩子们还没有被操作过,应该把它的孩子们加入栈中
- 否则,说明是第二次弹出该节点,访问node。
也就是说,第一次弹出,将node的孩子压入栈中,第二次弹出,访问node
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- TreeWalker.prototype.postOrder = function(node,callback) {
- var stack=[];
- stack.push(node);
- stack.push(node);
- while(stack.length != 0)
- {
- node = stack.pop();
- if(stack.length != 0 && node==stack[stack.length-1])
- {
- if(node.lastElementChild) stack.push(node.lastElementChild), stack.push(node.lastElementChild);
- if(node.firstElementChild) stack.push(node.firstElementChild), stack.push(node.firstElementChild);
- }
- else
- callback(node);
- }
-
- }