2) Rotate List

Hi Geeks! Today we going to see, how to rotate the linked list with fun.

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

Solution:

public ListNode rotateRight(ListNode head, int n)
{
    if (head==null||head.next==null)
      return head;
    ListNode dummy=new ListNode(0);
    dummy.next=head;
    ListNode fast=dummy,slow=dummy;

    int i;
    for (i=0;fast.next!=null;i++)//Get the total length 
    	fast=fast.next;
    
    for (int j=i-n%i;j>0;j--) //Get the i-n%i th node
    	slow=slow.next;
    
    fast.next=dummy.next; //Do the rotation
    dummy.next=slow.next;
    slow.next=null;
    
    return dummy.next;
}

Time Complexity : O(n)

Space Complexity: O(n) Since we have used extra dummy linkedlist😜

One thought on “2) Rotate List

  1. Pingback: 13) Remove Nth Node From End of List – Developers Inspired

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