/*

求二叉树的深度：递归和层序遍历法

*/

import java.util.Queue;

import java.util.LinkedList;

public class Solution {

public int TreeDepth(TreeNode pRoot)

{

if(pRoot == null){

return 0;

}

Queue<TreeNode> queue = new LinkedList<TreeNode>();

queue.add(pRoot);

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;

}

}

// 2递归

import java.lang.Math;

public class Solution {

public int TreeDepth(TreeNode root) {

if(root==null)

return 0;

int ldis =TreeDepth(root.left);

int rdis =TreeDepth(root.right);

return Math.max(ldis,rdis)+1;

}

}