第三章 队列【数据结构】【链队列】【循环队列】

最近越来越感觉到c语言指针的强大~~

#include<stdio.h>
#include<stdlib.h>
#define QElemType int
#define OK 1
#define ERROR 0
#define OVERFLOW 0
typedef int Status;
//------------单链表------------队列的链式存储结构 
typedef struct QNode {
    QElemType data;
    struct QNode *next;
}QNode,*QueuePtr;

typedef struct{
    QueuePtr front,rear;//队头指针和队尾指针 
}LinkQueue;
//-----------------基本函数操作----------------- 
Status InitQueue(LinkQueue &Q,int n)
{
    Q.front = Q.rear = (QueuePtr)malloc(sizeof(QNode));//构造一个空队列 
    if(!Q.front)
        exit(OVERFLOW);
    Q.front->next = NULL;
    printf("请输入n个数
");
    for(int i = 1; i <= n; i ++)//读入n个数,并依次加入队列 
    {
        QueuePtr p = (QueuePtr)malloc(sizeof(QNode));
        scanf("%d",&p->data);
        p->next = NULL;
        Q.rear->next = p;
        Q.rear = p;
    }
    return OK;
}
//销毁队列Q 
Status DestroyQueue(LinkQueue &Q)
{
    while(Q.front)
    {
        Q.rear = Q.front->next ;
        free(Q.front);
        Q.front = Q.rear ;
    }
    return OK;
}
//插入元素e为Q 的新的队尾元素 
Status EnQueue(LinkQueue &Q,QElemType &e)
{
    QueuePtr p = (QueuePtr)malloc(sizeof(QNode));
    if(!p)
        exit(OVERFLOW);//存储分配失败 
    p->data = e;
    p->next = NULL;
    Q.rear->next = p;
    Q.rear = p;
    return OK;
}
//若队列不为空，则删除Q的队头元素，用e返回其值，并返回OK，否则返回ERROR 
Status DeQueue(LinkQueue &Q,QElemType &e)
{
    if(Q.front == Q.rear )
        return ERROR;
    QueuePtr p = (QueuePtr)malloc(sizeof(QNode));
    p = Q.front->next ;
    e = p->data ;
    Q.front->next = p->next ;
    free(p);
    return OK;
}

void PrintQueue(LinkQueue *Q)//输出队列Q 中的元素 
{
    QueuePtr p = Q->front->next ;//将队列的头元素指针地址赋值给p 
    while(p!=NULL)
    {
        printf("%d ",p->data);
        p = p->next ;
    }
    printf("
");
}
int main() 
{
    LinkQueue Q;
    int n;
    printf("请输入n
");
    
    scanf("%d",&n);//读入n个数，加入队列 
    InitQueue(Q,n);//初始化队列 
    printf("初始化后的队列为：
");
    PrintQueue(&Q);//输出队列中的元素 
    
    int e;
    printf("请输入一个整数e
");
    scanf("%d",&e);//读入e 
    EnQueue(Q,e);//插入元素e为Q的新的队尾元素 
    printf("将e插入队尾后，队列更新为
");
    PrintQueue(&Q);//输出插入队尾后队列的值 
    
    DeQueue(Q,e);//删除Q的队头元素，用e返回其值 
    printf("删除队头元素后的队列为
");
    PrintQueue(&Q);//输出删除队头后的队列 
    
    DestroyQueue(Q);//销毁队列，释放存储空间 
    return 0;
}

 循环队列的实现

#include<stdio.h>
#include<stdlib.h>
typedef int  QElemType;
#define OVERFLOW 0
#define MAXSIZE 1000
typedef int Status;
#define OK 1
#define ERROR 0
typedef struct {
    QElemType *base;
    int front;
    int rear;
}SqQueue;

Status InitQueue(SqQueue &Q)
{
    int n;
    printf("请输入n
");
    scanf("%d",&n);
    Q.base = (QElemType*)malloc(MAXSIZE*sizeof(QElemType));
    if(!Q.base)
        exit(OVERFLOW);
    Q.front = Q.rear = 0;
    printf("请输入n个元素
");
    for(int i = 0; i < n; i ++)
    {
        scanf("%d",&Q.base[i]);
        Q.rear = (Q.rear +1)%MAXSIZE;
    }
    return OK;
} 

int QueueLength(SqQueue Q)
{
    return (Q.rear - Q.front +MAXSIZE)%MAXSIZE;
}

Status EnQueue(SqQueue &Q,QElemType e)
{
    if((Q.rear +1)%MAXSIZE==Q.front )
        return ERROR;
    Q.base[Q.rear +1] = e;
    Q.rear = (Q.rear + 1)%MAXSIZE;
    return OK;
}

Status DeQueue(SqQueue &Q,QElemType &e)
{
    if(Q.front == Q.rear )
        return ERROR;
    e = Q.base[Q.front];
    Q.front = (Q.front + 1)%MAXSIZE;
    return OK;
}

void PrintQueue(SqQueue S)
{
    SqQueue Q = S;
    while((Q.front+1)%MAXSIZE != Q.rear)
    {
        printf("%d ",Q.base[Q.front]);
        Q.front = (Q.front + 1)%MAXSIZE;
    }
    printf("
");
    return ;
}

int main()
{
    SqQueue Q;
    QElemType e;
    InitQueue(Q);
    printf("队列的长度为：%d
",QueueLength(Q));
    printf("请输入插入元素的值e:
");
    scanf("%d",&e);
    EnQueue(Q, e);
    printf("插入元素以后的队列值为：
");
    PrintQueue(Q);
    DeQueue(Q,e);
    printf("删除队头元素后的队列值为：
");
    PrintQueue(Q);
    return 0;
}