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Problem
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 = 2Output: 4->5->1->2->3->NULLExplanation:rotate 1 steps to the right: 5->1->2->3->4->NULLrotate 2 steps to the right: 4->5->1->2->3->NULLExample 2:
Input: 0->1->2->NULL, k = 4Output: 2->0->1->NULLExplanation:rotate 1 steps to the right: 2->0->1->NULLrotate 2 steps to the right: 1->2->0->NULLrotate 3 steps to the right: 0->1->2->NULLrotate 4 steps to the right: 2->0->1->NULL
Solution
class Solution {
public ListNode rotateRight(ListNode head, int k) {
if (head == null || head.next == null || k == 0) return head;
ListNode dummy = new ListNode(0);
dummy.next = head;
ListNode fast = dummy, slow = dummy;
int n = 0;
while (fast.next != null) {
fast = fast.next;
n++;
}
k = n-k%n;
while (k > 0) {
slow = slow.next;
k–;
}
fast.next = dummy.next;
dummy.next = slow.next;
slow.next = null;
return dummy.next;
}
}