4.29 leetcode -29 rotate-list

题目描述 Given a list, rotate the list to the right by k places, where k is non-negative. For example: Given1->2->3->4->5->NULLand k =2,

return4->5->1->2->3->NULL.

这个问题，我同学和我说，面试出过问题。

需要小心的点是，k > 链表长度，此时相当于又一个mod过程。

思路不难，两个指针，前后走就行。

/** * 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) { ListNode *pToEnd = head; ListNode *pNewEnd = head; ListNode *pNewHead; if(head == NULL) return NULL; int i = 0; for(; i < k ;i ++) { if(pToEnd->next == NULL)//k大于链表长度的话 pToEnd = head; else pToEnd = pToEnd->next; } while(pToEnd->next != NULL) { pToEnd = pToEnd->next; pNewEnd = pNewEnd->next; } pToEnd->next = head; pNewHead = pNewEnd->next; pNewEnd->next = NULL; return pNewHead; } };