递归实现指数型枚举

Status	Submit By	Time	Memory	Language	Code	Submit At
AC	duyusen	4ms	532 KiB	C++11(O2)	369 Bytes	2025-3-8 15:58:17
AC	tangyiqi	5ms	576 KiB	C++11(O2)	329 Bytes	2025-3-8 16:02:17
AC	lilyjiang	5ms	576 KiB	C++14(O2)	523 Bytes	2025-3-5 19:57:53
AC	maxinyue	5ms	596 KiB	C++11(O2)	355 Bytes	2025-3-8 15:57:53