#include<stdlib.h>
#include<string.h>
#include<stdio.h>
typedef struct LNode
{
	int data;
	struct LNode* next;
}LNode, * LinkList;


LinkList List_H(LinkList& L)               //头插法插入元素
{
	LNode* s;
	int x;
	L = (LinkList)malloc(sizeof(LNode));
	L->next = NULL;
	printf("请输入链表元素的值（输入-1结束）\n:");
	scanf_s("%d", &x);
	while (x != -1)
	{
		s = (LNode*)malloc(sizeof(LNode));
		s->next = NULL;
		s->data = x;
		s->next = L->next;
		L->next = s;
		scanf_s("%d", &x);


	}
	return L;
}



LinkList List_T(LinkList& L) {                        //尾插法循环插入元素
	LNode* s, * r;
	int x;
	L = (LinkList)malloc(sizeof(LNode));
	L->next = NULL;
	r = L;
	printf("请输入链表中元素的值:(输入9结束)\n");
	scanf_s("%d", &x);

	while (x != 9)
	{
		s = (LNode*)malloc(sizeof(LNode));
		s->data = x;
		s->next = NULL;                    //最后一个元素末尾置空；

		r->next = s;
		r = s;
		scanf_s("%d", &x);
	}
	return L;
}
LinkList PrintfList(LinkList L)                 //打印元素
{
	LNode* p;
	p = L->next;                             //p指向第1号元素
	if (p == NULL)
		printf("NULL");
	else
		printf("打印链表中的元素:");

	while (p != NULL)
	{

		printf("%d ", p->data);
		p = p->next;

	}
	return L;
}


LNode* GetElem(LinkList L, int i)          //查找第i号元素；
{
	int j = 1;
	LNode* p = L->next;
	if (i == 0)                           //头节点输出NULL；
		printf("NULL");
	if (i < 0)                       //不合理值处理
		printf("NULL");

	while (p != NULL && j < i)
	{
		p = p->next;
		j++;
	}
	return p;
}


LNode* Getdata(LinkList L, int e)
{
	LNode* p = L->next;
	while (p!= NULL && p->data != e)
	{
		p = p->next;
	}
	return p;

}

int LengthLink(LinkList L)
{
	int len = 0;
	LNode* p = L;
	while (p->next != NULL)
	{
		p=p->next;
		len++;
	}
	return len;
}



int main()                                    //主函数
{
	LinkList L;
	L = (LinkList)malloc(sizeof(LNode));
	

	while(1)
	{
	     printf("\n请输入接下来的操作:\n");
		 printf("1:创建表，输入元素并打印元素\n");
		 printf("2:寻找第i号元素并打印\n");
		 printf("3:寻找元素x\n");
		 printf("4:求表长\n");
		 printf("5:打印链表中所有元素:\n");
		 printf("-1:退出\n\n");
		 int x;
		 scanf_s("%d", &x);
		 int n,len;
		 int elem;
	     LNode* i, * p;
	
		 if (x == -1)
			 break;
		switch (x)
		{
		case 1:
			List_T(L);
			printf("\n");
			break;
		case 2:
			printf("查找第几号元素:");
			scanf_s("%d", &n);
			printf("\n打印出第%d号元素:", n);
			
			i = GetElem(L, n);
			printf("%d", i->data);
			printf("\n");
			break;
		case 3:
			printf("输入需要查找的元素:");
			scanf_s("%d", &elem);
			p = Getdata(L, elem);
			printf("\n找到了");
			printf("%d", p->data);
			printf("\n");
			break;
		case 4:
			len = LengthLink(L);
			printf("\n表长:%d", len);
			printf("\n");
			break;
		case 5:
			printf("链表中元素所有的值为:");
			PrintfList(L);
			break;
		}
	}

}