<算法编程> 两个栈实现一个队列

#include<iostream>
using namespace std;

typedef struct Node
{
    int num;
    Node* pNext;
}Stack,Queue;

//栈的入栈相当于 链表的头插
Stack* stack_push(Stack** pTop,int num)
{
    Stack* pNode = (Stack*)malloc(sizeof(Stack));
    pNode->num = num;
    pNode->pNext = NULL;

    pNode->pNext = *pTop;
    *pTop = pNode;
    
    return *pTop;
}

int stack_pop(Stack** pTop)
{
    if((*pTop) == NULL) return -1;

    Stack* pPop = *pTop;
    int num = pPop->num;
    
    *pTop = (*pTop)->pNext;
    free(pPop);
    pPop = NULL;
    
    return num;
}

void PrintStack(Stack* pTop)
{
    cout << "当前栈顶元素为：" << pTop->num << endl;
}

//队列的进栈
Queue* queue_push(Stack** pTop1,Stack** pTop2,int num)
{
    //首先判断 栈2中有没有元素 如果有 全部压回栈1中
    if((*pTop2) != NULL)
    {
        while((*pTop2) != NULL)
        {
            stack_push(pTop1,stack_pop(pTop2));
        }
    }

    //现有元素已经全部在栈1中 或栈1为空
    //直接压栈
    stack_push(pTop1,num);

    return (Queue*)pTop1;
}

int queue_pop(Stack** pTop1,Stack** pTop2)
{
    //判断栈1中有没有元素 如果有 就把栈1中的所有元素都压入栈2后弹出
    if((*pTop1) != NULL)
    {
        while((*pTop1) != NULL)
        {
            stack_push(pTop2,stack_pop(pTop1));
        }
    }

    return stack_pop(pTop2);
}

int main()
{
    Stack* pTop1 = NULL; //用来进栈的
    Stack* pTop2 = NULL; //用来出栈的
    /*stack_push(&pTop,1);
    stack_push(&pTop,2);
    stack_push(&pTop,3);
    stack_push(&pTop,4);
    PrintStack(pTop);
    cout << "弹出栈顶元素：" << stack_pop(&pTop) << endl;
    cout << "弹出栈顶元素：" << stack_pop(&pTop) << endl;
    cout << "弹出栈顶元素：" << stack_pop(&pTop) << endl;
    cout << "弹出栈顶元素：" << stack_pop(&pTop) << endl;
    cout << "弹出栈顶元素：" << stack_pop(&pTop) << endl;*/
    queue_push(&pTop1,&pTop2,1);
    queue_push(&pTop1,&pTop2,2);
    queue_push(&pTop1,&pTop2,3);
    queue_push(&pTop1,&pTop2,4);
    queue_pop(&pTop1,&pTop2);
    queue_pop(&pTop1,&pTop2);

    system("pause");
    return 0;
}