public class TreeNode {
int val = 0;
TreeNode left = null;
TreeNode right = null;
public TreeNode(int val) {
this.val = val;
}
}
public static int TreeDepth(TreeNode root) {
if(root==null){
return 0;
}
int right = TreeDepth(root.right);
int left= TreeDepth(root.left);
return Math.max(right,left)+1;
}