循环单链表的操作

创建循环单链表

// 循环链表
// 最后一个结点的指针指向头结点
// 
// 有时候可以设置尾指针，更方便表的连接操作
typedef struct Node
{
	int elem;
	struct Node * next;
}clinklist, *pclinklist;

生成循环单链表

• 函数声明

pclinklist clinklist_create(int size);

• 函数实现

pclinklist clinklist_create(int size)
{
	pclinklist node, head;
	head = (pclinklist)malloc(sizeof(clinklist));

	// 头结点 elem 表示链表大小，头结点 next 指向第一个元素
	// 尾巴结点指向第一个元素节点
	head->elem = size;
	head->next = NULL;

	node = head;

	for (int i = 0; i < size; i++)
	{
		node->next = (pclinklist)malloc(sizeof(clinklist));
		node = node->next;
		node->elem = rand() % 100;
		node->next = NULL;
	}
	node->next = head->next;

	return head;
}

插入

• 函数声明

void clinklist_insert(pclinklist list, int locate, int elem);

• 函数实现

void clinklist_insert(pclinklist plist, int location, int elem)
{
	if (location < 0 || location > plist->elem) return;

	pclinklist inode = (pclinklist)malloc(sizeof(clinklist));
	inode->elem = elem;
	inode->next = NULL;

	pclinklist prev = clinklist_find(plist, location - 1);
	pclinklist tail = clinklist_find(plist, plist->elem - 1);

	inode->next = prev->next;
	prev->next = inode;

	if (location == 0)
		tail->next = plist->next;

	clinklist_update_head(plist);
}

删除

• 函数声明

void clinklist_delete(pclinklist list, int locate);

• 函数实现

void clinklist_delete(pclinklist plist, int location)
{
	if (location < 0 || location >= plist->elem) return;

	pclinklist prev = clinklist_find(plist, location - 1);
	pclinklist tail = clinklist_find(plist, plist->elem - 1);

	pclinklist dnode = prev->next;
	prev->next = prev->next->next;
	free(dnode);

	if (location == 0)
		tail->next = plist->next;

	clinklist_update_head(plist);
}

遍历

• 函数声明

void clinklist_display(pclinklist plist);

• 函数实现

void clinklist_display(pclinklist plist)
{
	pclinklist node = plist->next;
	for (int i = 0; i < plist->elem; i++)
	{
		printf("%4d", node->elem);
		node = node->next;
	}
	printf("\n");
}

查找

• 函数声明

pclinklist clinklist_find(pclinklist list, int location);

• 函数实现

// -1 是 header 结点
pclinklist clinklist_find(pclinklist list, int location)
{
	if (location < -1 || location >= list->elem) return NULL;

	pclinklist node = list;

	for (int i = -1; i < location; i++)
	{
		node = node->next;
	}

	return node;
}

完整实例

• 头文件 clinklist.h

#pragma once
#ifndef CLINKLIST_H
#define CLINKLIST_H

// 循环链表
// 最后一个结点的指针指向头结点
// 
// 有时候可以设置尾指针，更方便表的连接操作
typedef struct Node
{
	int elem;
	struct Node * next;
}clinklist, *pclinklist;

pclinklist clinklist_create(int size);
void clinklist_insert(pclinklist list, int locate, int elem);
void clinklist_delete(pclinklist list, int locate);
void clinklist_display(pclinklist list);
pclinklist clinklist_find(pclinklist list, int location);
int clinklist_is_same(pclinklist head, pclinklist node);
int clinklist_is_empty(pclinklist list);
int clinklist_size(pclinklist list);
void clinklist_update_head(pclinklist list);

#endif

• 源文件 clinklist.c

#include 
#include 
#include "clinklist.h"

int main() {
	int size;
	int index = 0;
	pclinklist list;

	printf("输入此循环单链表的大小：");
	scanf_s("%d", &size);

	list = clinklist_create(size);
	clinklist_display(list);

	for (index = 0; index < size; index++)
	{
		pclinklist node = clinklist_find(list, index);
		printf("位置 %d 的值为：%d \n", index, node->elem);
	}

	printf("\n在位置5插入元素2后\n");
	clinklist_insert(list, 4, 2);
	clinklist_display(list);

	printf("\n在最后一个位置插入元素-1后\n");
	clinklist_insert(list, clinklist_size(list), -1);
	clinklist_display(list);

	printf("\n在位置0插入元素1111后\n");
	clinklist_insert(list, 0, 1111);
	clinklist_display(list);

	printf("\n删除位置3元素后\n");
	clinklist_delete(list, 2);
	clinklist_display(list);

	printf("\n删除位置1元素后\n");
	clinklist_delete(list, 0);
	clinklist_display(list);

	printf("\n删除位置最后的元素后\n");
	clinklist_delete(list, clinklist_size(list) - 1);
	clinklist_display(list);

	return 0;
}

pclinklist clinklist_create(int size)
{
	pclinklist node, head;
	head = (pclinklist)malloc(sizeof(clinklist));

	// 头结点 elem 表示链表大小，头结点 next 指向第一个元素
	// 尾巴结点指向第一个元素节点
	head->elem = size;
	head->next = NULL;

	node = head;

	for (int i = 0; i < size; i++)
	{
		node->next = (pclinklist)malloc(sizeof(clinklist));
		node = node->next;
		node->elem = rand() % 100;
		node->next = NULL;
	}
	node->next = head->next;

	return head;
}

void clinklist_display(pclinklist plist)
{
	pclinklist node = plist->next;
	for (int i = 0; i < plist->elem; i++)
	{
		printf("%4d", node->elem);
		node = node->next;
	}
	printf("\n");
}

void clinklist_insert(pclinklist plist, int location, int elem)
{
	if (location < 0 || location > plist->elem) return;

	pclinklist inode = (pclinklist)malloc(sizeof(clinklist));
	inode->elem = elem;
	inode->next = NULL;

	pclinklist prev = clinklist_find(plist, location - 1);
	pclinklist tail = clinklist_find(plist, plist->elem - 1);

	inode->next = prev->next;
	prev->next = inode;

	if (location == 0)
		tail->next = plist->next;

	clinklist_update_head(plist);
}

void clinklist_delete(pclinklist plist, int location)
{
	if (location < 0 || location >= plist->elem) return;

	pclinklist prev = clinklist_find(plist, location - 1);
	pclinklist tail = clinklist_find(plist, plist->elem - 1);

	pclinklist dnode = prev->next;
	prev->next = prev->next->next;
	free(dnode);

	if (location == 0)
		tail->next = plist->next;

	clinklist_update_head(plist);
}

// -1 是 header 结点
pclinklist clinklist_find(pclinklist list, int location)
{
	if (location < -1 || location >= list->elem) return NULL;

	pclinklist node = list;

	for (int i = -1; i < location; i++)
	{
		node = node->next;
	}

	return node;
}

int clinklist_is_same(pclinklist lnode, pclinklist rnode)
{
	return (lnode == rnode) ? 1 : 0;
}

int clinklist_is_empty(pclinklist list)
{
	return list->next == NULL;
}

int clinklist_size(pclinklist list)
{
	return list->elem;
}

void clinklist_update_head(pclinklist list)
{
	pclinklist node = list->next;
	int size = node == NULL ? 0 : 1;

	while ((node = node->next) != list->next)
		size++;

	list->elem = size;
}