树深度广度优先遍历

static void DFS(TreeNode root){
        Stack<TreeNode> stack = new Stack<>();
        stack.add(root);
        while (!stack.isEmpty()){
            TreeNode node = stack.pop();
            System.out.println(node.val);
            if(node.right!=null){
                stack.add(node.right);
            }
            if(node.left!=null){
                stack.add(node.left);
            }
        }
    }

    static void BFS(TreeNode root){
        Queue<TreeNode> queue = new LinkedList<>();
        queue.add(root);
        while (!queue.isEmpty()){
            TreeNode node = queue.remove();
            System.out.println(node.val);
            if(node.left!=null){
                queue.add(node.left);
            }
            if(node.right!=null){
                queue.add(node.right);
            }
        }
    }