import java.util.*;
/**
public class TreeNode {
    int val = 0;
    TreeNode left = null;
    TreeNode right = null;

    public TreeNode(int val) {
        this.val = val;

    }

}
*/
public class Solution {
    // 找树的深度,使用dfs,递归的思想,就是分别从根节点遍历左子树和右子树,来比较左右子树的深度,
    public int TreeDepth(TreeNode root) {
        if(root == null){
            return 0;
        }
        return Math.max(TreeDepth(root.left),TreeDepth(root.right)) + 1;
    }
}