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;

    }

}
*/
public class Solution {

    public int TreeDepth(TreeNode root) {
        if(root!=null){
            int left = TreeDepth(root.left);
            int right = TreeDepth(root.right);
            if(left>=right){
                return left+1;
            }else{
                return right+1;
            }
        }
        
        return 0;
    }
}