链队列

来源：互联网发布：儿童学编程编辑：程序博客网时间：2024/05/22 06:39

链队列是队列的链式表示和实现。主要操作包括：初始化、清空、销毁、判断是否为空、插入、删除、队列长度、获取队头元素。在实现的过程中，在队列的结构中添加了count，用来记录队列中元素的个数，这样无论在判定是否为空、求队列长度以及其他操作的实现中都可以简化。

#include <stdio.h>#include <stdlib.h>#include <malloc.h>#define OK 1#define ERROR 0#define OVERFLOW -1typedef struct QNode{    int data;    struct QNode *next;}QNode;typedef struct{    QNode *front;//队头指针    QNode *rear;//队尾指针    int count;//队列元素个数}LinkQueue;//队列初始化int InitQueue(LinkQueue *Q){    Q->front = Q->rear = (QNode *)malloc(sizeof(QNode));    if(!Q->front)        exit(OVERFLOW);    Q->rear->next =NULL;    Q->count = 0;    return OK;}//销毁队列int DestroyQueue(LinkQueue *Q){    while(Q->front)    {        Q->rear = Q->front->next;        free(Q->front);        Q->front = Q->rear;    }    return OK;}//清空队列int ClearQueue(LinkQueue *Q){    while(Q->front->next->next)    {        Q->front->next = Q->front->next->next;        free(Q->front);    }    free(Q->front->next);    Q->front->next = NULL;    Q->rear = Q->front;    Q->count = 0;    return OK;}//判断队列是否为空int QueueEmpty(LinkQueue *Q) {     if (Q->count == 0)         printf("Queue is empty\n");     else         printf("Queue is not empty\n");     return 0; }//队列长度 int QueueLength(LinkQueue *Q) {     int n;     n = Q->count;     return n; }//获取队头元素int GetHead (LinkQueue *Q){    int n;    QNode *P;    if (QueueLength(Q)==0)    {        printf("Queue don't have Head\n");    }    else    {        P = Q->front->next;        n = P->data;    }    return n;}//插入int InsertQueue(LinkQueue *Q, int n){    QNode *P;    P=(QNode *)malloc(sizeof(QNode));    if(!P)        exit(OVERFLOW);    P->data = n;    P->next = NULL;    Q->rear->next = P;    Q->rear = P;    Q->count ++;    return OK;}//删除int DeleteQueue(LinkQueue *Q){    QNode *P;    int n;    if(Q->front == Q->rear)        return ERROR;    P = Q->front->next;    n = P->data;    Q->front->next = P->next;    if(Q->rear == P)        Q->rear = Q->front;    free(P);    Q->count --;    return 0;}int main(){    LinkQueue *Q;    int i,k;    Q=(LinkQueue*)malloc(sizeof(LinkQueue));    InitQueue(Q);    int quit=1;    while(quit==1)    {        printf("1.Insert 2.Delete 3.GetHead 4.QueueLength 5.Empty 6.Clear 7.Destroy\n");        scanf("%d",&k);        getchar();        switch(k)        {            case 1:                printf("Insert number \n");                scanf("%d",&i);                InsertQueue(Q,i);                break;            case 2:                printf("Delete number is ");                DeleteQueue(Q);                printf("\n");                break;            case 3:                printf("Queue head is %d\n",GetHead(Q));                break;            case 4:                printf("Queue length is %d\n",QueueLength(Q));                break;            case 5:                QueueEmpty(Q);            case 6:                ClearQueue(Q);                QueueEmpty(Q);                break;            case 7:                DestroyQueue(Q);                break;        }    }    return 0;}

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