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


#define OK 1;
#define ERROR 0;
#define OVERFLOW 0; 
#define TURE 1;
#define FALSE 0;


typedef int Status;
typedef char QElemType;  //队型数据 

//链队中结点的定义
typedef struct QNode {
    QElemType data;  //数据域 
    struct QNode *next;  //指针域 
}QNode,*QueuePtr;

//链队的定义
typedef struct {
    QueuePtr front;  //队头指针 
    QueuePtr rear;  //队尾指针 
}LinkQueue; 


//链队的初始化
Status InitQueue(LinkQueue *queue){
    queue->front=queue->rear=(QueuePtr)malloc(sizeof(QNode));
    if(!queue->front) return OVERFLOW;
    queue->front->next=NULL;  //头结点next域置空 
    return OK;
}

//链队的销毁
Status DestroyQueue(LinkQueue *queue){
    QNode *p;
    while(queue->front){
        p=queue->front->next;
        free(queue->front);
        queue->front=p;
    }
    return OK;
}

//元素入队 
Status EnQueue(LinkQueue *queue,QElemType elem){
    QueuePtr p=(QueuePtr)malloc(sizeof(QNode));
    if(!p) return OVERFLOW;
    p->data=elem;
    p->next=NULL;
    queue->rear->next=p;
    queue->rear=p;
    return OK;
}

//元素出队
Status DeQueue(LinkQueue *queue,QElemType *elem){
    if(queue->front==queue->rear) return ERROR;
    QueuePtr p=queue->front->next;  //p指向首元(队头元素) 
    *elem=p->data;  //出队元素的值保存到elem
    queue->front->next=p->next;
    if(p==queue->rear) queue->rear=queue->front;  //如果出队的是最后一个元素
    free(p);
    return OK;
}

//取队头元素
QElemType GetHead(LinkQueue queue){
    if(queue.front==queue.rear) return ERROR;
    return queue.front->next->data;
}


int main(void){
    LinkQueue queue1;  //定义一个链队
    
    //初始化 
    Status initQueueResult = InitQueue(&queue1);
    printf("队列queue1初始化结果：%d\n",initQueueResult);
    
    //元素入队
    QElemType elem1='Y',elem2='C';
    Status enResult = EnQueue(&queue1,elem1);
    printf("入队执行结果：%d\n",enResult);
    EnQueue(&queue1,elem2); //将elem2也入队 
    printf("队尾元素值：%c\n",queue1.rear->data);
    
    //元素出队
    QElemType elem3;  //出队的数据放入elem3 
    Status deResult = DeQueue(&queue1,&elem3);
    printf("出队执行结果：%d\n",deResult);
    printf("出队元素值：%c\n",elem3);
    printf("队尾元素值：%c\n",queue1.rear->data);
    
    //取队头元素
    QElemType queueHeadValue = GetHead(queue1);
    printf("获取队头元素值：%c\n",queueHeadValue); 
    
    //链队销毁
    Status destroyResult = DestroyQueue(&queue1);
    printf("链队销毁结果：%d\n",destroyResult);
    
    printf("\nEND");
    return 0;
}