数据结构学习笔记 --- 队列（链队列）

#include "ds.h"

typedef 	int 	QElemType;

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

struct LinkQueue{
QueuePtr 	front, rear;
};

void InitQueue(LinkQueue &Q);
void DestroyQueue(LinkQueue &Q);
void ClearQueue(LinkQueue &Q);
Status QueueEmpty(LinkQueue Q);
int QueueLength(LinkQueue Q);
Status GetHead(LinkQueue Q, QElemType &e);
void EnQueue(LinkQueue &Q, QElemType e);
Status DeQueue(LinkQueue &Q, QElemType &e);
void QueueTraverse(LinkQueue Q, void(*vi)(QElemType));

// 带头结点的单链队列
void InitQueue(LinkQueue &Q)
{
Q.front = (QueuePtr)malloc(sizeof(QNode));
if (!Q.front) exit(OVERFLOW);

Q.front->next = NULL;
Q.rear = Q.front;

}
void DestroyQueue(LinkQueue &Q)
{
QueuePtr q, p = Q.front;

while (p)
{
q = p->next;
free(p);
p = q;
}

Q.front = Q.rear = NULL;
}
void ClearQueue(LinkQueue &Q)
{
QueuePtr q, p = Q.front->next;

while (p)
{
q = p->next;
free(p);
p = q;
}
Q.front->next = NULL;
Q.rear = Q.front;
}
Status QueueEmpty(LinkQueue Q)
{
if (Q.front == Q.rear)
return TRUE;
else
return FALSE;
}
int QueueLength(LinkQueue Q)
{
int i = 0;
QueuePtr p = Q.front->next;

while (p)
{
i++;
p = p->next;
}

return i;
}
Status GetHead(LinkQueue Q, QElemType &e)
{
if (Q.front->next)
{
memcpy(&e, &(Q.front->next->data), sizeof(QElemType));
return OK;
}
else
{
return FALSE;
}
}
void EnQueue(LinkQueue &Q, QElemType e)
{
QueuePtr p = (QueuePtr)malloc(sizeof(QNode));
if (!p) exit(OVERFLOW);

p->next = NULL;
memcpy(&(p->data), &e, sizeof(QElemType));
Q.rear->next = p;
Q.rear = p;
}
Status DeQueue(LinkQueue &Q, QElemType &e)
{
QueuePtr p = Q.front, q;
if (Q.front == Q.rear)
return FALSE;

q = p->next;
memcpy(&e, &(q->data), sizeof(QElemType));
p->next = q->next;
if (Q.rear == q)
Q.rear = Q.front;
free(q);

return OK;
}
void QueueTraverse(LinkQueue Q, void(*vi)(QElemType))
{
QueuePtr p = Q.front->next;

while (p)
{
vi(p->data);
p = p->next;
}
printf("\n");
}

void print(QElemType e)
{
printf("%d ", e);
}

int main()
{
int i;
QElemType d;
LinkQueue q;
InitQueue(q);
printf("成功地构造了一个空队列!\n");
printf("是否空队列？%d(1:空 0:否)  ",QueueEmpty(q));
printf("队列的长度为%d\n",QueueLength(q));
EnQueue(q,-5);
EnQueue(q,5);
EnQueue(q,10);
printf("插入3个元素(-5,5,10)后,队列的长度为%d\n",QueueLength(q));
printf("是否空队列？%d(1:空 0:否)  ",QueueEmpty(q));
printf("队列的元素依次为：");
QueueTraverse(q,print);
i=GetHead(q,d);
if(i==OK)
printf("队头元素是：%d\n",d);
DeQueue(q,d);
printf("删除了队头元素%d\n",d);
i=GetHead(q,d);
if(i==OK)
printf("新的队头元素是：%d\n",d);
ClearQueue(q);
printf("清空队列后,q.front=%u q.rear=%u q.front->next=%u\n",q.front,q.rear,q.front->next);
DestroyQueue(q);
printf("销毁队列后,q.front=%u q.rear=%u\n",q.front, q.rear);
}