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Solution.java
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Solution.java
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package g0001_0100.s0061_rotate_list;
// #Medium #Two_Pointers #Linked_List #Programming_Skills_II_Day_16 #Udemy_Linked_List
// #2023_08_11_Time_0_ms_(100.00%)_Space_41.1_MB_(94.89%)
import com_github_leetcode.ListNode;
/*
* Definition for singly-linked list.
* public class ListNode {
* int val;
* ListNode next;
* ListNode() {}
* ListNode(int val) { this.val = val; }
* ListNode(int val, ListNode next) { this.val = val; this.next = next; }
* }
*/
public class Solution {
public ListNode rotateRight(ListNode head, int k) {
if (head == null || k == 0) {
return head;
}
ListNode tail = head;
// find the count and let tail points to last node
int count = 1;
while (tail != null && tail.next != null) {
count++;
tail = tail.next;
}
// calculate number of times to rotate by count modulas
int times = k % count;
if (times == 0) {
return head;
}
ListNode temp = head;
// iterate and go to the K+1 th node from the end or count - K - 1 node from
// start
for (int i = 1; i <= count - times - 1 && temp != null; i++) {
temp = temp.next;
}
ListNode newHead = null;
if (temp != null && tail != null) {
newHead = temp.next;
temp.next = null;
tail.next = head;
}
return newHead;
}
}