剑指offer系列-用两个栈实现队列

#include<iostream>
#include<stdio.h>
#include<string.h>
#include<stack>
using namespace std;
template <typename T> class CQueue{
    public:
        //CQueue(void);
        //~CQueue(void);
        void appendTail(const T& node);
        T deleteHead();
    private:
        stack<T> stack1;
        stack<T> stack2;

};
template <typename T> void CQueue<T>::appendTail(const T& node){
    stack1.push(node);
}
template <typename T> T CQueue<T>::deleteHead(){
    if(stack2.size()<=0){
        while(stack1.size()>0){
            T& data = stack1.top();
            stack1.pop();
            stack2.push(data);
        }
    }
    if(stack2.size()==0){
        throw "error";
    }
    T head = stack2.top();
    stack2.pop();
    return head;
}
int main(){
    int n;
    char ch[10];
    int num;
    CQueue<int> cqueue;
    scanf("%d",&n);
    while(n--){
        scanf("%s",ch);
        if(strcmp("PUSH",ch)==0){
            scanf("%d",&num);
            cqueue.appendTail(num);
        }else{
            try{
                printf("%d\n",cqueue.deleteHead());
            }catch(const char * str){
                printf("-1\n");
            }
        }
    }
    return 0;
}