LeetCode Q61: 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.

	/**
	* 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)
	return head;
	int l=0;
	ListNode* p=head;
	ListNode* tail=p;
	while(p!=NULL){
	l++;
	tail=p;
	p=p->next;
	}
	k=k%l;
	p=head;
	for(int i=0; i<l-k-1; ++i){
	p=p->next;
	}
	tail->next=head;
	head=p->next;
	p->next=NULL;
	return head;
	}
	};

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