数据结构之顺序队列（优化版）

来源：互联网发布：soliworks小金球软件编辑：程序博客网时间：2024/06/09 23:35

上一篇文章我说了顺序队列的不足之处是常用的Append操作时间复杂度是O(n),

所以我们下面就把它优化成O(1)，闲话少说直接上代码。

第九个例子，顺序队列优化版的实现：

头文件

#ifndef _SEQQUEUE_H_#define _SEQQUEUE_H_typedef void SeqQueue;SeqQueue* SeqQueue_Create(int capacity);void SeqQueue_Destroy(SeqQueue* queue);void SeqQueue_Clear(SeqQueue* queue);int SeqQueue_Append(SeqQueue* queue, void* item);int SeqQueue_Length(SeqQueue* queue);int SeqQueue_Capacity(SeqQueue* queue);void* SeqQueue_Retrieve(SeqQueue* queue);void* SeqQueue_Header(SeqQueue* queue);#endif

我个人有点小小的强迫症，代码尽量要求简洁，所以没有注释，有什么不明白的可以留言。

实现文件

#include <stdio.h>#include <malloc.h>#include "SeqQueue.h"typedef unsigned int TSeqQueueNode;typedef struct tag_SeqQueue{    int length;    int capacity;    int front;    int rear;    TSeqQueueNode* node;        } TSeqQueue;SeqQueue* SeqQueue_Create(int capacity){            TSeqQueue* ret = NULL;        if (capacity >= 0)    {        ret = (TSeqQueue*)malloc(sizeof(TSeqQueue) + sizeof(TSeqQueueNode) * capacity);    }    if (ret)    {        ret->capacity = capacity;        ret->length = 0;        ret->front = 0;        ret->rear = 0;        ret->node = (TSeqQueueNode*)(ret + 1);    }        return ret;}void SeqQueue_Destroy(SeqQueue* queue){    free(queue);}void SeqQueue_Clear(SeqQueue* queue){    TSeqQueue* sQueue = (TSeqQueue*)queue;        if (sQueue != NULL)    {        sQueue->length = 0;        sQueue->front = 0;        sQueue->rear = 0;    }}int SeqQueue_Append(SeqQueue* queue, void* item){      TSeqQueue* sQueue = (TSeqQueue*)queue;    int ret = (sQueue != NULL) && (item != NULL);    ret = ret && ((sQueue->length + 1) <= sQueue->capacity);        if (ret)    {        sQueue->node[sQueue->rear] = (TSeqQueueNode)item;        sQueue->rear = (sQueue->rear + 1) % sQueue->capacity;             sQueue->length++;    }        return ret;  }int SeqQueue_Length(SeqQueue* queue){    TSeqQueue* sQueue = (TSeqQueue*)queue;    int ret = -1;        if (sQueue != NULL)    {        ret = sQueue->length;    }        return ret;}int SeqQueue_Capacity(SeqQueue* queue){       TSeqQueue* sQueue = (TSeqQueue*)queue;    int ret = -1;        if (sQueue != NULL)    {        ret = sQueue->capacity;    }        return ret;}void* SeqQueue_Retrieve(SeqQueue* queue){      TSeqQueue* sQueue = (TSeqQueue*)queue;    void* ret = SeqQueue_Header(queue);        if (ret)    {        sQueue->front = (sQueue->front + 1) % sQueue->capacity;        sQueue->length--;    }        return ret;}void* SeqQueue_Header(SeqQueue* queue){    TSeqQueue* sQueue = (TSeqQueue*)queue;    void* ret = NULL;        if ((sQueue != NULL) && (sQueue->length > 0))    {        ret = (void*)sQueue->node[sQueue->front];    }        return ret;}

跟顺序表实现差不多吧！！！其实数据结构很多东西都是通用的。

#include <stdio.h>#include <stdlib.h>#include "SeqQueue.h"int main(int argc, char *argv[]){    SeqQueue* queue = SeqQueue_Create(20);    int a[10] = {0};    int i = 0;        for (i = 0; i < 10; i++)    {        a[i] = i + 1;                SeqQueue_Append(queue, a + i);        }        printf("capacity:%d\n", SeqQueue_Capacity(queue));    printf("length:%d\n", SeqQueue_Length(queue));    printf("header:%d\n", *((int*)SeqQueue_Header(queue)));        while (SeqQueue_Length(queue) > 0)    {        printf("retrieve:%d\n", *((int*)SeqQueue_Retrieve(queue)));          }        SeqQueue_Clear(queue);    SeqQueue_Destroy(queue);         system("PAUSE");    return 0;}

测试文件跟上一个版本的一样，原封不动，测试的结果跟上一个版本的结果一样，

唯一的区别就是代码的效率提高了。

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