leetcode 061 —— 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->NULL and k = 2,
return 4->5->1->2->3->NULL.

思路：找到分割的位置

class Solution {
public:
	ListNode* rotateRight(ListNode* head, int k) {
		if (!head) return head;
		ListNode *loop = head;
		ListNode *l = head;
		ListNode *r = head;
		int len = 0;
		while (loop->next){   //记录链表长度，并将loop定位到最后一个节点
			len++;
			loop = loop->next;
		}
		len++;
		int n = len - k%len;
		if (n == len || n == 0) return head;
		
		while (n-1){
			l = l->next;
			n--;
		}
		r = l->next;
		l->next = nullptr;
		loop->next = head;
		return r;
	}
};