链队列

/*
链队列
LJK 2018-07-04
*/
#include<stdio.h>
#include<stdlib.h>
#include<math.h>

#define OK 1
#define ERROR 0
#define TRUE 1
#define FALSE 0

typedef int QElemType;
typedef int Status;

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

typedef struct
{
    QNode *front, *rear;
}LinkQueue;

// 初始化链队列时，生成一个头结点，此时front、rear同时指向头节点
// 头节点data中是随机值
Status InitQueue(LinkQueue *Q)
{
    Q->front = Q->rear = (QNode*)malloc(sizeof(QNode));
    if (!Q->front) exit(OVERFLOW);
    Q->front->next = NULL;
    return OK;
}

Status QueueEmpty(LinkQueue Q)
{
    if (Q.front == Q.rear) return TRUE;
    else return FALSE;
}

int QueueLen(LinkQueue Q)
{
    int i = 0;
    QNode *p;
    p = Q.front;
    while (p!=Q.rear)
    {
        i++;
        p = p->next;
    }
    return i;
}

// 入队操作
Status EnQueue(LinkQueue *Q, QElemType e)
{
    QNode *s = (QNode*)malloc(sizeof(QNode));
    if (!s) exit(OVERFLOW);
    s->data = e;
    s->next = NULL;
    Q->rear->next = s;
    Q->rear = s;
    return OK;
}

Status QueueTraverse(LinkQueue Q)
{
    QNode *p = Q.front->next;
    while (p)
    {
        printf("%d ", p->data);
        p = p->next;
    }
    printf("
");
    return OK;
}

Status GetHead(LinkQueue Q, QElemType *e)
{
    if (Q.front == Q.rear) return ERROR;
    *e = Q.front->next->data;
    return OK;
}

// 出队操作
Status DeQueue(LinkQueue *Q, QElemType *e)
{
    QNode *p;
    if (Q->front == Q->rear) return ERROR;
    p = Q->front->next;
    *e = p->data;
    Q->front->next = p->next;
    if (p == Q->rear) Q->rear = Q->front;
    free(p);
    return OK;
}

Status ClearQueue(LinkQueue *Q)
{
    QNode *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;
}

// 销毁队列
Status DestroyQueue(LinkQueue *Q)
{
    while (Q->front)
    {
        Q->rear = Q->front->next;
        free(Q->front);
        Q->front = Q->rear;
    }
    return OK; 
}

int main()
{
    int i;
    QElemType d;
    LinkQueue q;

    i = InitQueue(&q);
    if (i) printf("队列构造成功!!!
");
    printf("IsEmpty? %d (1:空  0:非空)
", QueueEmpty(q));
    printf("LenQueue = %d

", QueueLen(q));

    EnQueue(&q, -5);
    EnQueue(&q, 5);
    EnQueue(&q, 10);
    printf("插入三个元素后：
");
    printf("LenQueue = %d
", QueueLen(q));
    printf("IsEmpty? %d (1:空  0:非空)
", QueueEmpty(q));
    printf("QueueData:");
    QueueTraverse(q);
    printf("
");

    i = GetHead(q, &d);
    if (i == OK) printf("HeadData = %d
", d);
    DeQueue(&q, &d);
    printf("Delete HeadData:%d
", d);
    i = GetHead(q, &d);
    if (i == OK) printf("New HeadData = %d

", d);

    printf("QueueData:");
    QueueTraverse(q);
    printf("
");

    ClearQueue(&q);
    printf("Clear Queue:q.front = %p q.rear = %p  q.front->next = %p

", q.front, q.rear, q.front->next);

    DestroyQueue(&q);
    printf("Destroy Queue:q.front = %p q.rear = %p
", q.front, q.rear);

    getchar();
    return 0;
}