数据结构——基本数据结构之队列

 

循环队列
用一组抵制连续的存储单元依次存放从队头到队尾的元素
另外两个指针front和rear分别指示队列头元素和尾元素的位置

queue.h

#ifndef _QUEUE_H
#define _QUEUE_H

#define MaxQSize 100
typedef int ElemType;

typedef struct SqQueue...{
ElemType *base;
int front;
int rear;
}Queue;

int InitQueue(Queue **q);
int DestroyQueue(Queue **q);
int ClearQueue(Queue **q);
int QueueEmpty(Queue *q);
int QueueLength(Queue *q);
int GetHead(Queue *q, ElemType *e);
int EnQueue(Queue **q, ElemType e);
int DeQueue(Queue **q, ElemType *e);

#endif

queue.c

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

int InitQueue(Queue **q)
...{
(*q)->base = (ElemType *)malloc(MaxQSize * sizeof(ElemType));
if(!(*q)->base)
return 0;
(*q)->front = 0;
(*q)->rear = 0;

return 1;
}

int QueueEmpty(Queue *q)
...{
if(q->rear == q->front)
return 1;
else
return 0;
}

int QueueLength(Queue *q)
...{
return (q->rear - q->front + MaxQSize) % MaxQSize;
}

int EnQueue(Queue **q, ElemType e)
...{
if(((*q)->rear + 1) % MaxQSize == (*q)->front)
return 0;
(*q)->base[(*q)->rear] = e;
(*q)->rear = ((*q)->rear + 1) % MaxQSize;

return 1;
}

int DeQueue(Queue **q, ElemType *e)
...{
if((*q)->rear == (*q)->front)
return 0;
*e = (*q)->base[(*q)->front];
(*q)->front = ((*q)->front + 1) % MaxQSize;

return 1;
}

QueueMain.c

#include <stdio.h>
#include "queue.h"

int main(int argc, char **argv)
...{
ElemType e;
Queue *q;

q = (Queue *)malloc(sizeof(Queue));
InitQueue(&q);
while((e = getchar()) != '#')
...{
EnQueue(&q, e);
}
while(!QueueEmpty(q))
...{
DeQueue(&q, &e);
printf("%c ", e);
}

return 0;
}