学步园

#include <stdio.h>
#include <malloc.h>

typedef int ElemType;

typedef struct _LNode
{
	ElemType nData;
	struct _LNode* next;
}LNode,*pLineList;

//创建
pLineList InitList()
{
	pLineList pHead = (pLineList)malloc(sizeof(LNode));
	pHead->nData = 0;
	pHead->next = NULL;
	return pHead;
}

//销毁
void DestroyList(pLineList* pList)
{
	free(*pList);
	*pList = NULL;
}

//清空
void ClearList(pLineList* pList)
{
	*pList = NULL;
}

//是否为空
bool ListEmpty(pLineList pList)
{
	if (pList->next == NULL)
	{
		return true;
	}
	return false;
}

//长度
int ListLenght(pLineList pList)
{
	pLineList p = pList->next;
	int nCount = 0;
	while(p)
	{
		nCount++;
		p = p->next;
	}
	return nCount;
}

//得到第i个值
ElemType GetItem(pLineList pList, int i)
{
	if (pList->next == NULL)			//空链表
	{
		return -1;
	}

	pLineList p = pList->next;
	int n = 1;
	while(p && n<i)
	{
		p = p->next;
		n++;
	}

	if (!p || n > i)
	{
		return -1;
	}
	return pList->nData;
}

//与e的关系判断
int LocateList(pLineList pList,ElemType e)
{
	if (pList->nData < e)
	{
		return -1;
	}
	else if (pList->nData == e)
	{
		return 0;
	}
	
	return 1;
}

//返回前驱
LNode PriorList(pLineList pList, ElemType e)
{
	pLineList p= pList;
	while(p->next)
	{
		if (p->next->nData == e)
		{
			break;
		}
	}

	return *p;		
}

//返回后继
LNode NextList(pLineList pList, ElemType e)
{
	pLineList p= pList->next;
	while(p)
	{
		if (p->nData == e)
		{
			break;
		}
	}

	return *p->next;
}

//插入
void InsertList(pLineList* pList, int i, ElemType e)
{
	pLineList p = *pList;
	int n = 1;
	while(p && n<i)
	{
		p = p->next;
		n++;
	}

	if (!p || n > i)
	{
		return;
	}

  	LNode* pNode = (LNode*)malloc(sizeof(LNode));
	pNode->nData = e;
	pNode->next = p->next;
	p->next = pNode;
}

//删除
ElemType deleteList(pLineList* pList,int i)
{
	ElemType elem;
	pLineList p = *pList;
	int n = 1;
	while(p->next && n<i)
	{
		p = p->next;
		n++;
	}

	if (!p->next || n>i)
	{
		return -1;
	}

	pLineList q = p->next;
	p->next = q->next;
	
	elem = q->nData;
	free(q);
	q= NULL;
	return elem;

}

//输出
void PrintList(pLineList pList)
{
	pLineList p = pList->next;
	while(p)
	{
		printf("%d\n",p->nData);
		p = p->next;
	}
}

//合并
void mergeList(pLineList* pList1,pLineList* pList2)
{
	pLineList pList = *pList1;

	pLineList p = (*pList1)->next;
	pLineList q = (*pList2)->next;

	while(p&&q)
	{
		if (p->nData < q->nData)
		{
			pList->next = p;
			pList = p;
			p = p->next;
		}
		else
		{
			pList->next = q;
			pList = q;
			q = q->next;
		}
	}

	pList->next = p?p:q;
	free(*pList2);
	*pList2 = NULL;
}

//倒置
void ReverseList(pLineList* pList)
{
	pLineList pHead = *pList;
	pLineList p = (*pList)->next;

	pHead->next = NULL;

	while(p)
	{
		pLineList q = p;
		p = p->next;
		
		q->next = pHead->next;
		pHead->next = q;
	}
}

//查找倒数第k个值
ElemType findK(pLineList pList,int k)
{
	pLineList pk = pList;
	int n = 0;
	while(pk && n < k)
	{
		n++;
		pk = pk->next;
	}

	if (!pk || n > k)
	{
		return -1;
	}

	pLineList p = pList;
	while(pk && p)
	{
		p = p->next;
		pk = pk->next;
	}
	return p->nData;
}

//是否有环
bool isLoop(pLineList pList)
{
	pLineList pShow = pList;
	pLineList pFast = pList->next;

	while(pShow && pFast->next)
	{
		if (pShow == pFast)
		{
			return true;
		}
		pShow = pShow->next;
		pFast = pFast->next->next; 
	}
	return false;
}

int main()
{
	pLineList pLine = InitList();

	if (ListEmpty(pLine))
	{
		printf("Empty\n");
	}
	else
	{
		printf("Not Empty\n");
	}

	InsertList(&pLine,1,6);
	InsertList(&pLine,1,5);
	InsertList(&pLine,1,4);
	InsertList(&pLine,1,3);
	InsertList(&pLine,1,2);
	InsertList(&pLine,1,1);

	deleteList(&pLine,5);


	pLineList pLine1 = InitList();

	if (ListEmpty(pLine1))
	{
		printf("Empty\n");
	}
	else
	{
		printf("Not Empty\n");
	}

	InsertList(&pLine1,1,6);
	InsertList(&pLine1,1,5);
	InsertList(&pLine1,1,4);
	InsertList(&pLine1,1,3);
	InsertList(&pLine1,1,2);
	InsertList(&pLine1,1,1);


	mergeList(&pLine,&pLine1);

	ReverseList(&pLine);


	printf("%d\n",ListLenght(pLine));

	if (isLoop(pLine))
	{
		printf("有环\n");
	}
	else
	{
		printf("无环\n");
	}

	
	PrintList(pLine);

	printf("%d\n",findK(pLine,3));
	DestroyList(&pLine);
	return 0;
}