用两个栈实现队列

来源：互联网发布：vb.net do while 编辑：程序博客网时间：2024/05/16 11:42

原理：

由于栈是先进后出的，所以，让数据先进入一个栈中，然后依次从栈顶弹出，在依次进入另一个栈中，最后，从另一个栈中弹出，并输出，这样就变为先进先出了，实现了我们的队列

实现代码

//linklist.h

#ifndef __LINKLIST_H__#define __LINKLIST_H__typedef struct linklistnode {    struct linklistnode *next;    int item;       //自身的一些数据和其他的数据}LinkListNode;typedef struct linklist {    LinkListNode header;    int length;}LinkList;LinkList *LinkList_Create();void LinkList_Destroy(LinkList *list);void LinkList_Clear(LinkList *list);int LinkList_Length(LinkList *list);int LinkList_Insert(LinkList *list, LinkListNode *node, int pos);LinkListNode *LinkList_Get(LinkList *list, int pos);LinkListNode *LinkList_Delete(LinkList *list, int pos);#endif //__LINKLIST_H__

//linklist.c

#include <stdlib.h>#include "linklist.h"LinkList *LinkList_Create(){    LinkList *ret = NULL;    ret = malloc(sizeof(LinkList));    if ( ret != NULL ) {        ret->length      = 0;        ret->header.next = NULL;    }    return ret;}void LinkList_Destroy(LinkList *list){    free(list);}void LinkList_Clear(LinkList *list){    if ( list != NULL ) {        list->length      = 0;        list->header.next = NULL;    }}int LinkList_Length(LinkList *list){    int ret = -1;    if ( list != NULL ) {        ret = list->length;    }    return ret;}int LinkList_Insert(LinkList *list, LinkListNode *node, int pos){    int ret = list!=NULL && node!=NULL && pos>=0;    if ( ret ) {        int i;        LinkListNode *cur = (LinkListNode*)list;        for (i=0; i<pos && cur->next!=NULL; i++) {            cur = cur->next;        }        node->next = cur->next;        cur->next = node;        list->length++;    }    return ret;}LinkListNode *LinkList_Get(LinkList *list, int pos){    LinkListNode *ret = NULL;    if ( list!=NULL && (0<=pos && pos<list->length) ) {        int i;        LinkListNode *cur = (LinkListNode*)list;        for (i=0; i<pos; i++)            cur = cur->next;        ret = cur->next;    }    return ret;}LinkListNode *LinkList_Delete(LinkList *list, int pos){    LinkListNode *ret = NULL;    if ( list!=NULL && (0<=pos&&pos<list->length) ) {        int i;        LinkListNode *cur = (LinkListNode*)list;        for (i=0; i<pos; i++)            cur = cur->next;        ret = cur->next;        cur->next = ret->next;        list->length--;    }    return ret;}

//linkstack.h

#ifndef __LINKSTACK_H__#define __LINKSTACK_H__typedef struct linkstacknode {    struct linkstacknode *next;    void *item;}LinkStackNode;typedef void LinkStack;LinkStack *LinkStack_Create();void LinkStack_Destroy(LinkStack *stack);void LinkStack_Clear(LinkStack *stack);int LinkStack_Push(LinkStack *stack, void *item);void *LinkStack_Pop(LinkStack *stack);void *LinkStack_Top(LinkStack *stack);int LinkStack_Size(LinkStack *stack);#endif //__LINKSTACK_H__

//linkstack.c

#include <stdio.h>#include <stdlib.h>#include <string.h>#include "linkstack.h"#include "linklist.h"LinkStack *LinkStack_Create(){    return LinkList_Create();}void LinkStack_Destroy(LinkStack *stack){    LinkStack_Clear(stack);    LinkList_Destroy(stack);}void LinkStack_Clear(LinkStack *stack){    while ( LinkStack_Size(stack) > 0 )        LinkStack_Pop(stack);}int LinkStack_Push(LinkStack *stack, void *item){    LinkStackNode *node = malloc(sizeof(LinkStackNode));    int ret = stack!=NULL && item!=NULL && node!=NULL;    if ( ret ) {        memset(node, 0x00, sizeof(*node));        node->item = item;        ret = LinkList_Insert(stack, (LinkListNode*)node, 0);    }    if ( !ret ) {        free(node);    }    return ret;}void *LinkStack_Pop(LinkStack *stack){    LinkStackNode *node = NULL;    void *ret = NULL;    node = (LinkStackNode*)LinkList_Delete(stack, 0);//返回要删除的节点，给node    if ( node != NULL ) {        ret = node->item;        free(node);    }    return ret;}void *LinkStack_Top(LinkStack *stack){    LinkStackNode *node= NULL;    void *ret = NULL;    node = (LinkStackNode*)LinkList_Get(stack, 0);    if ( node != NULL ) {        ret = node->item;    }    return ret;}int LinkStack_Size(LinkStack *stack){    return LinkList_Length(stack);}

//squeue.h

#ifndef __SQUEUE_H__#define __SQUEUE_H__#include "linkstack.h"typedef struct squeue{    LinkStack *inStack;     //进数据的栈    LinkStack *outStack;    //出数据的栈}SQueue;SQueue *SQueue_Create();void SQueue_Destroy(SQueue *queue);void SQueue_Clear(SQueue *queue);int SQueue_Append(SQueue *queue, void *item);void *SQueue_Retrieve(SQueue *queue);void *SQueue_Header(SQueue *queue);int SQueue_Length(SQueue *queue);#endif //__SQUEUE_H__

//squeue.c

#include <stdio.h>#include <stdlib.h>#include "linkstack.h"#include "squeue.h"SQueue *SQueue_Create(){    SQueue *ret = malloc(sizeof(SQueue));    if( ret!=NULL )    {        ret->inStack = LinkStack_Create();        ret->outStack = LinkStack_Create();//只要有一个栈创建失败了，那么我们就应该把我们创建的栈给销毁掉        if( ret->inStack==NULL || ret->outStack==NULL )        {            LinkStack_Destroy(ret->inStack);               LinkStack_Destroy(ret->outStack);             free(ret);            ret = NULL;        }    }    return ret;}void SQueue_Destroy(SQueue *queue){    SQueue_Clear(queue);    free(queue);}void SQueue_Clear(SQueue *queue){    if( queue!=NULL )    {        LinkStack_Clear(queue->inStack);         LinkStack_Clear(queue->outStack);     }}//入队int SQueue_Append(SQueue *queue, void *item){    int ret = queue!=NULL;    if( ret )    {        ret = LinkStack_Push(queue->inStack, item);    }    return ret;}//出队void *SQueue_Retrieve(SQueue *queue){    void *ret = NULL;    if( queue != NULL )    {        if( LinkStack_Size(queue->outStack) == 0 )  //out为空的时候        {            while ( LinkStack_Size(queue->inStack) > 0 )//同时in不为空,那么            {                LinkStack_Push(queue->outStack, LinkStack_Pop(queue->inStack));                 //从in里面弹出，并进入out里面             }        }        ret = LinkStack_Pop(queue->outStack); //out不为空的时候，直接让它弹出    }    return ret;}//队头void *SQueue_Header(SQueue *queue){    void *ret = NULL;    if( queue != NULL )    {        if( LinkStack_Size(queue->outStack) == 0 )  //out为空的时候        {            while ( LinkStack_Size(queue->inStack) > 0 )//同时in不为空,那么            {                LinkStack_Push(queue->outStack, LinkStack_Pop(queue->inStack));                 //从in里面弹出，并进入out里面             }        }        ret = LinkStack_Top(queue->outStack); //out不为空的时候，直接让Top取出    }    return ret;}//求长度int SQueue_Length(SQueue *queue){    int ret = -1;    if( queue != NULL )    {        ret = LinkStack_Size(queue->inStack) + LinkStack_Size(queue->outStack);     }    return ret;}

//main.c

#include <stdio.h>#include <stdlib.h>#include "squeue.h"int main( void ){    SQueue *queue = SQueue_Create();    int i;    int a[5] = {11,22,33,44,55};    for(i=0; i<5; i++)    {        SQueue_Append(queue, a+i);     }    //SQueue_Append(queue, a);     while ( SQueue_Length(queue) > 0 )    {        printf("%d ",*(int *)SQueue_Retrieve(queue));    }    printf("\n");    SQueue_Destroy(queue);    return 0;}

//Makefile

.PHONY : main cleanCC=gcc -gmain: main.o linklist.o linkstack.o squeue.o    $(CC) $^ -o $@clean:    rm -rf *.o  main

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