两个栈实现一个队列——栈和队列面试题（2）

题目要求：规定用两个栈实现一个队列，实现内部函数

"test.cpp"

#include<iostream>using namespace std;#include<stack>template<class T>class TwoStackFromQueue{public:TwoStackFromQueue(){}void Push(const T& data){if(PushStack.empty()){if(!PopStack.empty()){while(!PopStack.empty()){PushStack.push(PopStack.top());PopStack.pop();}PushStack.push(data);}else{PushStack.push(data);}}else{PushStack.push(data);}}void Pop(){if(PopStack.empty()){if(!PushStack.empty()){while(!PushStack.empty()){PopStack.push(PushStack.top());PushStack.pop();}PopStack.pop();}else{PopStack.pop();}}else{PopStack.pop();}}T& Front(){if(!PopStack.empty()){return PopStack.top();}else{while(!PushStack.empty()){PopStack.push(PushStack.top());PushStack.pop();}return PopStack.top();}}T& Back(){if(!PushStack.empty()){return PushStack.top();}else{while(!PopStack.empty()){PushStack.push(PopStack.top());PopStack.pop();}return PushStack.top();}}size_t Size(){if(PushStack.empty()){return PopStack.size();}else{return PushStack.size();}}bool Empty(){if(PushStack.empty()){return PopStack.empty();}else{return PushStack.empty();}}private:stack<T> PushStack;stack<T> PopStack;};void test(){TwoStackFromQueue<int> q;q.Push(7);q.Push(3);q.Push(2);q.Push(4);q.Push(6);q.Push(9);q.Push(0);cout<<"end = "<<q.Back()<<endl;cout<<"begin = "<<q.Front()<<endl;cout<<"size = "<<q.Size()<<endl;cout<<endl;q.Pop();q.Pop();cout<<"end = "<<q.Back()<<endl;cout<<"begin = "<<q.Front()<<endl;cout<<"size = "<<q.Size()<<endl;}int main(){test();return 0;}