做项目时需要对tree树进行删除，因为在删除某个节点时，要对这个节点下的所有节点进行删除，所以使用了递归来获取所有需要删除的节点，然后只需对返回的集合进行操作即可，递归方法现已上传(Do the project need to delete the tree tree, because in removing a node, to all nodes on this node are deleted, so use recursion to obtain all need to delete nodes, a recursive method has been uploaded)