LeetCode: Rotate List

两个边界条件没考虑到，少数次过

/**
 * 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) {
        // Start typing your C/C++ solution below
        // DO NOT write int main() function
        ListNode *tmp = head;
        if (!head) return NULL;
        int n = 0;
        while (tmp) {
            n++;
            tmp = tmp->next;
        }
        k %= n;
        ListNode *p = head;
        tmp = head;
        for (int i = 0; i < n-k-1; i++) tmp = tmp->next;
        ListNode *q = tmp->next;
        if (!q) return head;
        head = q;
        tmp->next = NULL;
        while (q->next) q = q->next;
        q->next = p;
        return head;
    }
};

 C#

/**
 * Definition for singly-linked list.
 * public class ListNode {
 *     public int val;
 *     public ListNode next;
 *     public ListNode(int x) { val = x; }
 * }
 */
public class Solution {
    public ListNode RotateRight(ListNode head, int k) {
        ListNode tmp = head;
        if (head == null) return null;
        int n = 0;
        while (tmp != null) {
            n++;
            tmp = tmp.next;
        }
        k %= n;
        ListNode p = head;
        tmp = head;
        for (int i = 0; i < n-k-1; i++) tmp = tmp.next;
        ListNode q = tmp.next;
        if (q == null) return head;
        head = q;
        tmp.next = null;
        while (q.next != null) q = q.next;
        q.next = p;
        return head;
    }
}