Rotate List

Given a list, rotate the list to the right by k places, where k is non-negative.

For example: Given 1->2->3->4->5->nullptr and k = 2, return 4->5->1->2->3->nullptr.

思路。

1.链接成环

2.从首个节点，继续走len-k个节点，断环

//从右边起第K个位置旋转
LinkNode * rotate(LinkNode *head,int k)
{
	LinkNode *dummy = new LinkNode(-1);
	dummy->next = head;
	LinkNode *cur = head;
	LinkNode *pre,*tmp;
	int len = 1;

	//找到最后一个节点
	while(cur->next)
	{
		len++;
		cur=cur->next;
	}

	//连接成环
	cur->next = head;

	if(k>len)
		k=k%len;

	pre = dummy;
	//从起点走len-k步，断开
	for(int i=0;i<len-k;i++)
	{
		//找到断开的前驱节点
		pre = pre->next;		
	}
	tmp = pre->next;
	pre->next = NULL;
	dummy->next = tmp;

	head=dummy->next;
	delete dummy;
	return head;
}