232. 用栈实现队列https://leetcode.cn/problems/implement-queue-using-stacks/solutions/2776991/232-yong-zhan-shi-xian-dui-lie-by-joker-zdgqs 225. 用队列实现栈https://leetcode.cn/problems/implement-stack-using-queues/solutions/2777028/225-yong-dui-lie-shi-xian-zhan-by-joker-qkl4z