队列编程

队列

typedef struct QNode
{
  QElemType data;
  struct QNode *next;
}*QueuePtr;

typedef struct Queue
{
  QueuePtr front,rear; //对头队尾指针

}LinkQueue;

Status InitQueue(LinkQueue **Q)
{//构造一个空队列

  if(!((*Q)->front = (*Q)->rear =(struct QNode *)malloc(sizeof(struct QNode))))
  exit(OVERFLOW);
  (*Q)->front->next = NULL;
  return OK;
}

Status DestroyQueue(LinkQueue *Q)
{//销毁队列Q

  while(Q->front)
  {
    Q->rear = Q->front->next;
    free(Q->front);
    Q->front = Q->rear;
  }
  return OK;
}

Status ClearQueue(LinkQueue *Q)
{//将Q清为空

  QueuePtr p,q;
  Q->rear = Q->front;
  p = Q->front->next;
  Q->front->next = NULL;
    while(p)
    {
      q = p;
      p=p->next;
      free(q);
    }
  return OK;
}

Status QueueEmpty(LinkQueue *Q)
{//若Q为空队列，则返回TRUE，否则返回FALSE

  if(Q->front == Q->rear)
  {
    return TRUE;
  }
  else
  {
    return FALSE;
  }
}

int QueueLength(LinkQueue *Q)
{//求队列的长度

  int i=0;
  QueuePtr p;
  p = Q->front;
  while(Q->rear !=p)
  {
    i++;
    p=p->next;
  }
  return i;
}

Status GetHead(LinkQueue *Q,QElemType *e)
{//若队列不空，用e返回Q的队头元素，并返回OK ，否则返回ERROR;

  QueuePtr p;
  if(Q->front == Q->rear)
    return ERROR;
  p=Q->front->next;
  *e = p->data;
  return OK;
}

Status EnQueue(LinkQueue *Q,QElemType e)
{//插入元素e为Q的新的队尾元素

  QueuePtr p;
  if(!(p = (QueuePtr)malloc(sizeof(struct QNode))))
    exit(OVERFLOW);
  p->data = e;
  p->next = NULL;
  Q->rear->next = p;
  Q->rear = p;
  return OK;
}

Status DeQueue(LinkQueue *Q,QElemType *e)
{//若队列不空，删除Q的对头元素，用e返回其值，并返回OK，否则返回ERROR

  QueuePtr p;
  if(Q->front == Q->rear)
    return ERROR;
  p = Q->front->next;
  *e = p->data;
  Q->front->next = p->next;
  if(Q->rear == p)
    Q->rear = Q->front;
  free(p);
  return OK;
}

Status QueueTraverse(LinkQueue *Q,void(*vi)(QElemType))
{// 从队头到队尾依次对队列Q中每个元素调用函数vi().

  QueuePtr p;
  p = Q->front->next;
  while(p)
  {
    vi(p->data);
    p=p->next;
  }
  printf("\n");
  return OK;
}