输入一个单向链表，输出该链表中倒数第 k 个结点

class ListNode
{
public:
ListNode()
{
pNext	= NULL;
nValue  = 0;
}
ListNode* pNext;
int nValue;
};
ListNode* CreaList()
{
int nValue;
ListNode* Head = NULL;
ListNode* ListIndex = NULL;
while(cin >> nValue)
{
if (Head == NULL)
{
Head = new ListNode();
Head->nValue = nValue;
ListIndex = Head;
}
else
{
ListNode* newNode = new ListNode();
newNode->nValue = nValue;
ListIndex->pNext = newNode;
ListIndex = newNode;
}
}

//
cout << "Print List;" << endl;
PrintList(Head);

return Head;
}

void PrintList(ListNode* Head)
{
for (ListNode* pNode = Head; pNode != NULL; pNode = pNode->pNext)
{
cout << pNode->nValue << " ";
}
cout << endl;
}

//运用两个节点 可以达到通过一次遍历完成输出倒数第K个节点
void PrintTheLastK(ListNode* Head, int K)
{
if (Head == NULL)
{
cout << "number of list less then " << K << endl;
return;
}

ListNode*  firstPoint = Head;
ListNode*  secondPoint = Head;

for (int i = 1; i < K ; i++)
{
secondPoint = secondPoint->pNext;
if (secondPoint == NULL)
{
cout << "number of list less then " << K << endl;
return;
}
}

while(1)
{
if (secondPoint->pNext == NULL)
{
cout << "result:" << firstPoint->nValue << endl;
return;
}
firstPoint = firstPoint->pNext;
secondPoint = secondPoint->pNext;
}
}

//拓展
//输入一个单向链表。如果该链表的结点数为奇数，输出中间的结点；如果链表结点数为偶数，输出中间两个结点前面的一个
void PrintMidNode(ListNode* Head)
{
if (Head == NULL)
{
return;
}

ListNode* firstNode = Head;
ListNode* secondNode = Head;

while (1)
{
if (secondNode->pNext == NULL || secondNode->pNext->pNext == NULL)
{
cout << "result:" << firstNode->nValue << endl;
return;
}

secondNode = secondNode->pNext->pNext;
firstNode  = firstNode->pNext;
}
}