C语言数据结构——循环链表

C语言数据结构——循环链表

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

typedef int ElemType;

typedef struct node{
	ElemType data;
	struct node *next;
}Node;

Node* initList()
{
	Node *head = (Node*)malloc(sizeof(Node));
	head->data = 0;
	head->next = head;
	return head;
}

//初始化循环链表

Node* getTail(Node *L)
{
	Node *p = L;
	while(p->next != L)
	{
		p = p->next;
	}
	return p;
}
//获得尾结点

Node* insertTail(Node *tail,ElemType e,Node *head)
{
	Node *p = (Node*)malloc(sizeof(Node));
	p->data = e;
	p->next = head;
	tail->next = p;
	return p;
}
//尾插法

int insertNode(Node *L,int pos,ElemType e)
{
	Node *p = L;
	int i = 0;
	while(i < pos - 1)
	{
		p = p->next;
		i++;
		if(p == L)
		{
			return 0;
		}
	}
	Node *q = (Node*)malloc(sizeof(Node));
	q->data = e;
	q->next = p->next;
	p->next = q;
	return 1;
}
//指定位置插入数据

int deleteNode(Node *L,int pos)
{
	Node *p = L;
	int i = 0;
	while(i < pos - 1)
	{
		p = p->next;
		i++;
		if(p->next == L)
		{
			return 0;
		}
	}
	Node *q = p->next;
	p->next = q->next;
	free(q);
	return 1;
}
//指定位置删除数据

void listNode(Node *L)
{
	Node *p = L->next;
	while(p != L)
	{
		printf("%d ",p->data);
		p = p->next;
	}
	printf("\n");
}
//遍历

int listLength(Node *L)
{
	Node *p = L->next;
	int i = 0;
	while(p != L)
	{
		p = p->next;
		i++;
	}
	printf("%d\n",i);
	return i;
}
//获取链表长度

void freeNode(Node *L)
{
	Node *p = L->next;
	while(p != L)
	{
		Node *q = p->next;
		free(p);
		p = q;
	}
	L->next = L;
}
//释放循环链表（不包括头结点）

int main()
{
	Node *list = initList();
	Node *tail = getTail(list);
	tail = insertTail(tail,10,list);
	tail = insertTail(tail,20,list);
	tail = insertTail(tail,30,list);
	listNode(list);
	insertNode(list,2,15);
	listNode(list);
	deleteNode(list,3);
	listNode(list);
	listLength(list);
	freeNode(list);
	listNode(list);
	free(list);
	return 0;
}