促销中“满X优惠”问题的两种解法：动态规划和枚举法。 https://blog.csdn.net/only_on_one/article/details/52337397 https://juejin.im/post/5b5dbcf8f265da0fa86750d1 https://www.cnblogs.com/warcraft/p/11013723.html
