设有头指针和尾指针，原来是个空队，然后开始入队！
typedef struct queue1
{
    int data;
    struct queue1 *next;
}queue;

typedef struct
{
    queue *front;
    queue *end;
}lqueue;

void init_lqueue(lqueue lq)       //设置一个空队
{
    lq.front=(queue *)malloc(sizeof(queue));
    lq.end=(queue *)malloc(sizeof(queue));
    lq.front->next=NULL;
    lq.end=lq.front;
}
queue *enqueue(lqueue lq,int y)  //入队操作
{
    queue *s;
    queue *head;
    if(lq.front!=lq.end)
    {
        s=(queue *)malloc(sizeof(queue));
        s->data=y;
        s->next=NULL;
        lq.end->next=s;
        lq.end=s;
        head=lq.front;
    }
    else
    {
        s=(queue *)malloc(sizeof(queue));
        s->data=y;
        s->next=NULL;
        lq.front=s;
        lq.end=s;
        head=s;
    }
    return head;
}

帮看下入队操作，怎么处理头指针和尾指针？

???