C++11 数据结构3 线性表的循环链式存储，实现，测试

上一节课，我们学了线性表单向存储结构（也就是单链表），这个是企业常用的技术，且是后面各种的基本，一定要牢牢掌握，如果没有掌握，下面的课程会云里雾里。

一，循环链表

1、什么是循环链表

— 概念上：
1、任何数据元素都有一个前驱和一个后继
2、所有的数据元素的关系构成一个逻辑的环

— 实现上：
1、循环链表是一种特殊的单链表
2、尾结点的指针域保存了首结点的地址

2、循环链表的逻辑构成

二循环链表的插入示意图

头插法第一次插入

头插法非第一次插入

删除非第一个元素

删除第一个元素

三代码实现

.h实现

#ifndef _003CIRCLELIST_H_
#define _003CIRCLELIST_H_

typedef void CircleList;  //要返回给上层的list 的首地址为 void *,为了阅读起名为CircleList

typedef struct _tag_CircleListNode  //list 中的节点
{
	struct _tag_CircleListNode* next;
}CircleListNode;


//创建循环链表
CircleList* CircleList_Create();


//销毁循环链表
void CircleList_Destroy(CircleList* list);


//清空循环列表
void CircleList_Clear(CircleList* list);


//循环列表中目前存在的元素个数
int CircleList_Length(CircleList* list);


//给循环列表中插入元素，node为要插入的元素的值，pos为位置
int CircleList_Insert(CircleList* list, CircleListNode* node, int pos);


//从循环列表中的pos 位置获得具体的值
CircleListNode* CircleList_Get(CircleList* list, int pos);


//从循环列表中删除pos位置的数据
CircleListNode* CircleList_Delete(CircleList* list, int pos);


//从循环列表中删除 数据 为node 的点
CircleListNode* CircleList_DeleteNode(CircleList* list, CircleListNode* node);



CircleListNode* CircleList_Reset(CircleList* list);



CircleListNode* CircleList_Current(CircleList* list);



CircleListNode* CircleList_Next(CircleList* list);



#endif

底层实现

#include "003CircleList.h"
#include "stdio.h"
#include "stdlib.h"
#include <string.h>


typedef struct _tag_CircleList{
	CircleListNode header;
	CircleListNode* slider; //多了一个游标
	int length;
} TCircleList;

CircleList* CircleList_Create(){
	TCircleList* ret = (TCircleList*)malloc(sizeof(TCircleList));
	if (ret == NULL) {
		printf("CircleList_Create func malloc error\n");
		return ret;
	}
	memset(ret,0,sizeof(TCircleList));
	ret->length = 0;
	ret->header.next = NULL;
	ret->slider = NULL;
	return ret;
}

void CircleList_Destroy(CircleList* list) // O(1)
{
	free(list);
}



void CircleList_Clear(CircleList* list){
	TCircleList* sList = (TCircleList*)list;
	if (sList != NULL)
	{
		sList->length = 0;
		sList->header.next = NULL;
		sList->slider = NULL;
	}
}

int CircleList_Length(CircleList* list){
	TCircleList* sList = (TCircleList*)list;
	int ret = -1;
	if (sList != NULL){
		ret = sList->length;
	}
	return ret;
}

int CircleList_Insert(CircleList* list, CircleListNode* node, int pos) // O(n)
{
	TCircleList* sList = (TCircleList*)list;
	int ret = (sList != NULL) && (pos >= 0) && (node != NULL);
	int i = 0;
	if (ret){
		CircleListNode* current = (CircleListNode*)sList;//current指向头部
		for (i = 0; (i < pos) && (current->next != NULL); i++)
		{
			current = current->next;
		}
		//假设我们要插入的是pos =3，头结点不算，下来从0,1,2,3,4,5,6开始计算
		//循环完成后，current刚好是在 pos=2的位置，
		//要变成的是 2  node   3 ，也就是说node->next要是3
		node->next = current->next;
		//current的->next，现在也是2，指向新的节点node
		current->next = node;

		if (sList->length == 0){
		//如果是第一次插入将slider的指向node
			sList->slider = node;

		}
		sList->length++;

		//如果是头插法，还需要做事情，让最后一个元素链接到这个新节点，
		if (current == (CircleListNode*)sList) {
			CircleListNode * last = CircleList_Get(list,sList->length-1);
			last->next = node;
		}
		//此处要理解，需结合图来看，后续会将 头插法，尾插法，中间插入法的三种图示画一下，方便理解
	}
	return ret;
}



CircleListNode* CircleList_Get(CircleList* list, int pos) // O(n)
{
	TCircleList* sList = (TCircleList*)list;
	CircleListNode* ret = NULL;
	int i = 0;
	if ((sList != NULL) && (pos >= 0)){
		CircleListNode* current = (CircleListNode*)sList;
		for (i = 0; i < pos; i++)
		{
			current = current->next;
		}
		ret = current->next;
	}
	return ret;
}



CircleListNode* CircleList_Delete(CircleList* list, int pos) // O(n)
{
	TCircleList* sList = (TCircleList*)list;
	CircleListNode* ret = NULL;
	int i = 0;
	if ((sList != NULL) && (pos >= 0)){
		CircleListNode* current = (CircleListNode*)sList;
		CircleListNode* first = sList->header.next;
		CircleListNode* last = (CircleListNode*)CircleList_Get(sList, sList->length - 1);
		for (i = 0; i < pos; i++){
			current = current->next;
		}
		ret = current->next;
		current->next = ret->next;
		sList->length--;
		//如果删除的第一个结点。要额外处理
		if (first == ret){
			//让头结点的next要重新指向，指向的内容是保存在 被删除的节点的next中的。
			sList->header.next = ret->next;
			//让最后一个节点的next也要重新指向，指向的内容是保存在 被删除的节点的next中的。
			last->next = ret->next;
		}

		//如果删除的元素刚好是 游标指向的元素，则将游标往下移动
		if (sList->slider == ret){
			sList->slider = ret->next;
		}

		//如果list只有一个元素，删除后，就没有元素了，那么就需要将
		if (sList->length == 0){
			sList->header.next = NULL;
			sList->slider = NULL;
		}
	}
	return ret;
}

CircleListNode* CircleList_DeleteNode(CircleList* list, CircleListNode* node) // O(n)
{
	TCircleList* sList = (TCircleList*)list;
	CircleListNode* ret = NULL;
	int i = 0;
	if (sList != NULL){
		CircleListNode* current = (CircleListNode*)sList;
		for (i = 0; i < sList->length; i++){
			if (current->next == node){
				ret = current->next;
				break;
			}
			current = current->next;
		}
		if (ret != NULL){
			CircleList_Delete(sList, i);
		}
	}
	return ret;
}

CircleListNode* CircleList_Reset(CircleList* list) // O(1)
{
	TCircleList* sList = (TCircleList*)list;
	CircleListNode* ret = NULL;
	if (sList != NULL){
		sList->slider = sList->header.next;
		ret = sList->slider;
	}
	return ret;
}

CircleListNode* CircleList_Current(CircleList* list) // O(1)
{
	TCircleList* sList = (TCircleList*)list;
	CircleListNode* ret = NULL;

	if (sList != NULL){
		ret = sList->slider;
	}
	return ret;
}

CircleListNode* CircleList_Next(CircleList* list) // O(1)
{
	TCircleList* sList = (TCircleList*)list;
	CircleListNode* ret = NULL;
	if ((sList != NULL) && (sList->slider != NULL)){
		ret = sList->slider;
		sList->slider = ret->next;
	}
	return ret;
}

测试代码

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

extern "C" {
#include "003CircleList.h"
}

using namespace std;


struct Value
{
	CircleListNode header;
	int v;
};

int main(int argc, char *argv[]){
	int i = 0;
	CircleList* list = CircleList_Create();
	struct Value v1;
	struct Value v2;
	struct Value v3;
	struct Value v4;
	struct Value v5;
	struct Value v6;
	struct Value v7;
	struct Value v8;
	v1.v = 1;
	v2.v = 2;
	v3.v = 3;
	v4.v = 4;
	v5.v = 5;
	v6.v = 6;
	v7.v = 7;
	v8.v = 8;

	CircleList_Insert(list, (CircleListNode*)&v1, CircleList_Length(list));
	CircleList_Insert(list, (CircleListNode*)&v2, CircleList_Length(list));
	CircleList_Insert(list, (CircleListNode*)&v3, CircleList_Length(list));
	CircleList_Insert(list, (CircleListNode*)&v4, CircleList_Length(list));
	for (i = 0; i <  CircleList_Length(list); i++)
	{
		struct Value* pv = (struct Value*)CircleList_Get(list, i);
		printf("%d\n", pv->v);
	}

	//注意这里，这时候list除了头结点外，只有4个元素，1,2,3,4，对应0,1,2,3
	//代码中插入的pos =5，相当于在1和2中间插入一个5.
	CircleList_Insert(list, (CircleListNode*)&v5, 5);

	//因此如下的循环后，打印出来的是 1,5,2,3,4
	for (i = 0; i < CircleList_Length(list); i++)
	{
		struct Value* pv = (struct Value*)CircleList_Get(list, i);
		printf("%d\n", pv->v);
	}

	CircleList_Delete(list, 0);//删除第一个元素，将1删除了

	//再次打印是 5 2 3 4  5 2 3 4
	for (i = 0; i < 2 * CircleList_Length(list); i++)
	{
		struct Value* pv = (struct Value*)CircleList_Get(list, i);
		printf("%d\n", pv->v);
	}

	printf("\n");
	while (CircleList_Length(list) > 0){
		struct Value* pv = (struct Value*)CircleList_Delete(list, 0);
		printf("%d\n", pv->v);
	}

	printf("aaaaaa\n");



	CircleList_Insert(list, (CircleListNode*)&v1, 0);
	CircleList_Insert(list, (CircleListNode*)&v2, 0);
	CircleList_Insert(list, (CircleListNode*)&v3, 0);
	CircleList_Insert(list, (CircleListNode*)&v4, 0);
	CircleList_Insert(list, (CircleListNode*)&v5, 0);
	CircleList_Insert(list, (CircleListNode*)&v6, 0);
	CircleList_Insert(list, (CircleListNode*)&v7, 0);
	CircleList_Insert(list, (CircleListNode*)&v8, 0);

	//注意，这里是用的头插法，因此是8,7,6,5,4,3,2,1，但是第一个插入的是1，因此游标指向1，又因为是循环的，因此下一个是8，结果是1,8,7,6,5,4,3,2
	for (i = 0; i < CircleList_Length(list); i++){
		struct Value* pv = (struct Value*)CircleList_Next(list);
		printf("%d\n", pv->v);
	}

	printf("bbbbbbbbbb\n");

	//游标reset 是指向的第一个元素
	CircleList_Reset(list);


	//1,2,3 将3剔除队列的游戏，游标reset后，指向的是8，因此123，将3剔除队列的有些结果为 6,3，8,4,7，1,5,2
	while (CircleList_Length(list) > 0){
		struct Value* pv = NULL;
		for (i = 1; i < 3; i++){
			CircleList_Next(list);
		}
		printf("ccc\n");//游标reset之后，指向数字8，往后移动了2次，就是指向6
		pv = (struct Value*)CircleList_Current(list);
		printf("%d\n", pv->v);
		CircleList_DeleteNode(list, (CircleListNode*)pv);
	}
	CircleList_Destroy(list);
	return 0;

}