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 == nullptr || k <= 0) return head;
int len = listLength(head);
k %= len;
if(k == 0) return head;
ListNode *p = head, *new_head = head, *new_end = head;
for(int i = 0; i < k; i++)
p = p->next;
while(p->next)
{
p = p->next;
new_end = new_end->next;
}
new_head = new_end->next;
new_end->next = nullptr;
p->next = head;
return new_head;
}
int listLength(ListNode *head)
{
int len = 0;
while(head)
{
len++;
head = head->next;
}
return len;
}
};