链表翻转。给出一个链表和一个数k，比如链表1→2→3→4→5→6，k=2，翻转后2→1→4→3→6→5。

链表翻转。给出一个链表和一个数k，比如链表1→2→3→4→5→6，k=2，翻转后2→1→4→3→6→5，若k=3,翻转后3→2→1→6→5→4，若k=4，翻转后4→3→2→1→5→6，用程序实现Node* RotateList(Node* list,
size_t k).

思路：取出长度为k的链表将其翻转，在链接到链表里。

#include<iostream>
using namespace std;

typedef struct LNode {
int Value;
struct LNode* Next;
}LNode;

LNode* reverseList(LNode* pHead) {
if (NULL == pHead || NULL == pHead->Next)
return pHead;
LNode* pNode;
LNode* pNewHead = NULL;
while (pHead) {
pNode = pHead;
pHead = pHead->Next;
pNode->Next = pNewHead;
pNewHead = pNode;
}
return pNewHead;
}

LNode* getLastNode(LNode* pHead) {
while (NULL != pHead->Next)
pHead = pHead->Next;
return pHead;
}

LNode* swapListByK(LNode* pHead, int k) {
if (k <= 1)
return pHead;
int pos;
LNode* pNode = pHead;
LNode* pNewHead;
LNode* pNextNode;
LNode* pLastNode = NULL;;
pHead = NULL;
while (pNode)
{
pos = 0;
pNewHead = pNode;
while (pNode && pos < k - 1) {
pNode = pNode->Next;
pos++;
}

if (pNode)
{
pNextNode = pNode->Next;
pNode->Next = NULL;
if (NULL != pLastNode)
{
pLastNode->Next = NULL;
}
pNewHead = reverseList(pNewHead);
if (NULL == pHead)
pHead = pNewHead;
else
pLastNode->Next = pNewHead;

pNode = getLastNode(pNewHead);
pNode->Next = pNextNode;
pLastNode = pNode;
pNode = pNextNode;
}
else
break;
}
return pHead;
}

void printList(LNode* pHead) {
LNode* pNode = pHead;
while (pNode) {
cout << pNode->Value << " ";
pNode = pNode->Next;
}
cout << endl;
}

LNode* createList(int* arr, int length) {
LNode* pHead = NULL;
LNode* pTemp, *pNode;
for (int i = 0; i < length; i++) {
pNode = (LNode*)malloc(sizeof(LNode));
pNode->Value = arr[i];
pNode->Next = NULL;
if (NULL == pHead)
pHead = pNode;
else
pTemp->Next = pNode;
pTemp = pNode;
}
return pHead;
}

void destroyList(LNode* pHead) {
LNode* pNode;
while (pHead) {
pNode = pHead;
pHead = pHead->Next;
free(pNode);
}
}

int main()
{
int arr[] = {1, 2, 3, 4, 5, 6, 7, 8, 9};
int length = sizeof(arr) / sizeof(arr[0]);
LNode* pHead = createList(arr, length);

pHead = swapListByK(pHead, 4);

printList(pHead);
destroyList(pHead);
system("pause");
return 0;
}