[LeetCode]Rotate List

题目描述:(链接)

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

.

解题思路:

注意k会大于链表长度： k % length.

/**
* 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 || k == 0) return head;

int length = 1;
ListNode *cur = head;
for (; cur->next != nullptr ; cur = cur->next) {
++length;
}
k = length - k % length;

cur->next = head;
for (int i =0; i < k; i++) {
cur = cur->next;
}

head = cur->next;
cur->next = nullptr;

return head;
}
};