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有了front使得取出顺序队列首元素的操作不用再移动后面的数据元素节点,时间复杂度变为O(1);有了rear使得链式队列的插入操作不用遍历整个队列,时间复杂度也是O(1)
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);
-
- void* SeqQueue_Retrieve(SeqQueue* queue);
-
- void* SeqQueue_Header(SeqQueue* queue);
-
- int SeqQueue_Length(SeqQueue* queue);
-
- int SeqQueue_Capacity(SeqQueue* queue);
-
-
- #endif

模块文件
- #include <malloc.h>
- #include "SeqQueueV2.h"
-
- typedef unsigned int TSeqQueueNode;
-
- typedef struct _tag_SeqQueue{
- int capacity;
- int length;
- int front;//指向队列头部,实质是一个下标
- int rear;//指向队列尾部,实质是一个下标
- TSeqQueueNode* node;
- }TSeqQueue;
-
-
- SeqQueue* SeqQueue_Create(int capacity)
- {
- TSeqQueue* ret = NULL;
- if(capacity > 0){
- ret = (TSeqQueue*)malloc(sizeof(TSeqQueue) + sizeof(TSeqQueueNode)*capacity);
- }
- if(ret != NULL){
- ret->capacity = capacity;
- ret->length = 0;
- ret->front = 0;//一开始的时候都为0
- ret->rear = 0;
- ret->node = (TSeqQueueNode*)(ret+1);//通过指针运算使得node指向真正的数据元素节点
- }
- 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) && (sQueue->length < sQueue->capacity);
-
- if(ret){
- sQueue->node[sQueue->rear] = (TSeqQueueNode)item;
-
- sQueue->rear = (sQueue->rear + 1) % sQueue->capacity;//注意这个技巧,循环使用队列中的空间
-
- sQueue->length++;
- }
- return ret;
- }
-
- void* SeqQueue_Retrieve(SeqQueue* queue)
- {
- TSeqQueue* sQueue = (TSeqQueue*)queue;
- void* ret = SeqQueue_Header(queue);
-
- if(sQueue != NULL){
- sQueue->front = (sQueue->front + 1) % sQueue->capacity;注意这个技巧,循环使用队列中的空间
- 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]);//注意类型转换
- }
- 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;
-
- }

- #include <stdio.h>
- #include <stdlib.h>
- #include "SeqQueueV2.h"
-
- /* run this program using the console pauser or add your own getch, system("pause") or input loop */
-
- int main(int argc, char *argv[])
- {
- SeqQueue* queue = SeqQueue_Create(6);
- int a[10] = {0};
- int i = 0;
-
- for(i=0; i<10; i++)
- {
- a[i] = i + 1;
-
- SeqQueue_Append(queue, a + i);
- }
-
- printf("Header: %d\n", *(int*)SeqQueue_Header(queue));
- printf("Length: %d\n", SeqQueue_Length(queue));
- printf("Capacity: %d\n", SeqQueue_Capacity(queue));
-
- while( SeqQueue_Length(queue) > 0 )
- {
- printf("Retrieve: %d\n", *(int*)SeqQueue_Retrieve(queue));
- }
-
- printf("\n");
-
- for(i=0; i<10; i++)
- {
- a[i] = i + 1;
-
- SeqQueue_Append(queue, a + i);
-
- printf("Retrieve: %d\n", *(int*)SeqQueue_Retrieve(queue));
- }
-
- SeqQueue_Destroy(queue);
-
- return 0;
- }

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