61. Rotate List
难度:Medium
刷题内容
原题连接
- https://leetcode.com/problems/rotate-list/
内容描述
Given a linked list, rotate the list to the right by k places, where k is non-negative.
Example 1:
Input: 1->2->3->4->5->NULL, k = 2
Output: 4->5->1->2->3->NULL
Explanation:
rotate 1 steps to the right: 5->1->2->3->4->NULL
rotate 2 steps to the right: 4->5->1->2->3->NULL
Example 2:
Input: 0->1->2->NULL, k = 4
Output: 2->0->1->NULL
Explanation:
rotate 1 steps to the right: 2->0->1->NULL
rotate 2 steps to the right: 1->2->0->NULL
rotate 3 steps to the right: 0->1->2->NULL
rotate 4 steps to the right: 2->0->1->NULL
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/**
* 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) {
int len = 0;
ListNode* h = head;
ListNode* pre;
while(h)
{
++len;
pre = h;
h = h ->next;
}
if(!len)
return head;
int count1 = len - k % len;
if(count1 == len)
return head;
h = head;
ListNode* tail;
while(count1)
{
tail = h;
h = h ->next;
--count1;
}
pre ->next = head;
tail ->next = nullptr;
return h;
}
};
