剑指offer之二叉树的深度

题目描述
输入一棵二叉树，求该树的深度。从根结点到叶结点依次经过的结点（含根、叶结点）形成树的一条路径，最长路径的长度为树的深度。

/**public class TreeNode {    int val = 0;    TreeNode left = null;    TreeNode right = null;    public TreeNode(int val) {        this.val = val;    }}*/

递归做法：

public class Solution {    public int TreeDepth(TreeNode root) {        if(root==null)            return 0;        return Math.max(TreeDepth(root.left),TreeDepth(root.right))+1;    }}

非递归做法[层次遍历]：

import java.util.*;public class Solution {    public int TreeDepth(TreeNode root)    {        if(root == null){            return 0;        }        Queue<TreeNode> queue = new LinkedList<TreeNode>();        queue.add(root);        int depth = 0, count = 0, nextCount = 1;        while(queue.size()!=0){            TreeNode top = queue.poll();            count++;            if(top.left != null){                queue.add(top.left);            }            if(top.right != null){                queue.add(top.right);            }            if(count == nextCount){                nextCount = queue.size();                count = 0;                depth++;            }        }        return depth;    }}