二叉树的深度

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) return 0;        int leftCount = TreeDepth(root.left)+1;        int rightCount = TreeDepth(root.right)+1;        int count = Math.max(leftCount, rightCount);        return count;    }}