Given the head
of a linked list, rotate the list to the right by k
places.
Example 1:
Input: head = [1,2,3,4,5], k = 2 Output: [4,5,1,2,3]
Example 2:
Input: head = [0,1,2], k = 4 Output: [2,0,1]
Constraints:
- The number of nodes in the list is in the range
[0, 500]
. -100 <= Node.val <= 100
0 <= k <= 2 * 109
Companies:
Microsoft, Amazon, Bloomberg
Related Topics:
Linked List, Two Pointers
Similar Questions:
// OJ: https://leetcode.com/problems/rotate-list/
// Author: github.com/lzl124631x
// Time: O(N)
// Space: O(1)
class Solution {
int getLength(ListNode *head) {
int ans = 0;
for (; head; head = head->next) ++ans;
return ans;
}
public:
ListNode* rotateRight(ListNode* head, int k) {
if (!head) return nullptr;
int len = getLength(head);
k %= len;
if (k == 0) return head;
auto p = head, q = head;
while (k--) q = q->next;
while (q->next) p = p->next, q = q->next;
auto ans = p->next;
p->next = nullptr;
q->next = head;
return ans;
}
};
// OJ: https://leetcode.com/problems/rotate-list/
// Author: github.com/lzl124631x
// Time: O(N)
// Space: O(1)
class Solution {
public:
ListNode* rotateRight(ListNode* head, int k) {
if (!head) return nullptr;
int len = 1;
auto p = head;
while (p->next) p = p->next, ++len;
p->next = head;
k = len - k % len;
while (k--) p = p->next;
auto ans = p->next;
p->next = nullptr;
return ans;
}
};