20.链式队列

运行截图:

完整代码:

#include <stdio.h>
#include <stdlib.h>

#define datatype int

typedef struct queue
{
    datatype data;
    struct queue *pNext;
}Queue,*PQueue;

//入队 从尾部入,从头部出
PQueue enq(PQueue phead, datatype data)
{
    PQueue pnew = (PQueue)malloc(sizeof(Queue));
    pnew->data = data;
    pnew->pNext = NULL;
    if (phead == NULL)
    {
        phead = pnew;//直接插入
    }
    else
    {
        PQueue ptemp = phead;
        //循环到尾部
        while (ptemp->pNext != NULL)
        {
            ptemp = ptemp->pNext;
        }
        ptemp->pNext = pnew;//尾部插入
    }
    return phead;
}

//出队
PQueue deq(PQueue phead, datatype *pdata)
{
    if (phead == NULL)
    {
        return NULL;
    }
    else
    {
        *pdata = phead->data;//获取弹出的数据
        PQueue ptemp = phead->pNext;
        free(phead);
        phead = ptemp;
    }
}

//显示
void show(PQueue phead)
{
    if (phead == NULL)
    {
        return;
    }
    else
    {
        printf("%5d", phead->data);
        show(phead->pNext);//递归调用
    }
}

void main()
{
    Queue *phead = NULL;
    for (int i = 0; i < 10; i++)
    {
        phead = enq(phead, i);
        printf("\nqueue");
        show(phead);
    }

    while (phead != NULL)
    {
        datatype data;
        phead = deq(phead, &data);
        printf("\ndequeue%d", data);
        printf("\nqueue");
        show(phead);
    }

    system("pause");
}