[leetcode]Rotate List

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.

算法思路：

注意处理边界情况，k > length，需要取余的，坑爹。k == 0 || length时，不作处理

public class Solution {
    public ListNode rotateRight(ListNode head, int n) {
        ListNode hhead = new ListNode(0);
        hhead.next = head;
        ListNode tail = hhead;
        int length = 0;
        while(tail.next != null){
            length++;
            tail = tail.next;
        }
        if(length == 0 || n == 0) return head;
        if(n >= length) n %= length;
        ListNode pre = hhead;
        for(int i = 0; i < length - n; pre = pre.next,i++);
        tail.next = hhead.next;
        hhead.next = pre.next;
        pre.next = null;
        return hhead.next;
    }
}