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Rotate List.cpp
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Rotate List.cpp
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/**
* Definition for singly-linked list.
* struct ListNode {
* int val;
* ListNode *next;
* ListNode(int x) : val(x), next(NULL) {}
* };
*/
class Solution {
public:
ListNode* rotateRight(ListNode* head, int k) {
if(head==NULL||head->next==NULL||k<=0)
{
return head;
}
ListNode* pHead=head;
ListNode* pNode=head;
ListNode* pLast=head;
ListNode* pNodek=head;
int n=0;
while(pNode!=NULL)//出来以后pLast指向链表最后一个结点,而pNode=pLast->next是NULL
{
pLast=pNode;
pNode=pNode->next;
n++;
}
if(k>n)//这个如果k是大于链表长度的,那么就去掉整数倍部分
{
k=k%n;
}
if(k==n||k==0)//如果k=0或者n那就不用反转
{
return head;
}
int i=n-k;
while(i>0)//此时pNodek已经到了该选择的那个点,且记录pNodek的前一个结点pNode。
{
pNode=pNodek;
pNodek=pNodek->next;
i--;
}
pNode->next=pLast->next;
pLast->next=pHead;
head=pNodek;
return head;
}
};