求二叉樹的高度

package com.djx.tree;

public class Tree_Depth {
	 
	public static void main(String[] args) {
		// TODO Auto-generated method stub
		TreeNode root=new TreeNode(0);
		TreeNode node1=new TreeNode(1);
		TreeNode node2=new TreeNode(2);
		TreeNode node3=new TreeNode(3);
		TreeNode node4=new TreeNode(4);
		root.left=node1;
		root.right=node2;
		node1.left=node3;
		node3.right=node4;
		System.out.println(Solution.maxDepth(root));
	}
	public static class Solution {
		public static int maxDepth(TreeNode root) {
			if (root==null)
				return 0;
			else return Math.max(maxDepth(root.left)+1,maxDepth(root.right)+1);
		}
	}
}
class TreeNode{
	int val;
	TreeNode left;
	TreeNode right;
	public TreeNode(int x) {
		// TODO Auto-generated constructor stub
		val=x;
	}
}