Implement the following operations of a stack using queues.
Notes:You must useonlystandard operations of a queue — which means onlypush to back,peek/pop from front,size, andis emptyoperations are valid.Depending on your language, queue may not be supported natively. You may simulate a queue by using a list or deque (double-ended queue), as long as you use only standard operations of a queue.You may assume that all operations are valid (for example, no pop or top operations will be called on an empty stack).
两个队列，永远有一个为空，插入时，，插入到不为空的队列中，如果都为空则任意；弹出时，把不为空队列中的所有元素（最后一个除外）转移到另一队列当中，并将最后一个不插入，直接删除即可。如果两个队列均为空，则说明栈为空。
class Stack {public:// Push element x onto stack.void push(int x) {//在非空队列中插入if (aqueue.empty())bqueue.push(x);elseaqueue.push(x);}// Removes the element on top of the stack.void pop() {if (aqueue.empty()){//转移while (bqueue.size() != 1){int tmp = bqueue.front();aqueue.push(tmp);bqueue.pop();}bqueue.pop();}else{while (aqueue.size() != 1){int tmp = aqueue.front();bqueue.push(tmp);aqueue.pop();}aqueue.pop();}}// Get the top element.int top() {int tmp;if (aqueue.empty()){while (!bqueue.empty()){tmp= bqueue.front();aqueue.push(tmp);bqueue.pop();}}else{while (!aqueue.empty()){tmp = aqueue.front();bqueue.push(tmp);aqueue.pop();}}return tmp;}// Return whether the stack is empty.bool empty() {return (aqueue.empty() && bqueue.empty());}private:queue<int> aqueue;queue<int> bqueue;};
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可是，我却迈不开步伐，怎么也走不出那个圈……
