21.rotate list.java

/**
 * 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; }
 * }
 */
class Solution {
    public ListNode rotateRight(ListNode head, int k) {
        if(head==null || head.next==null || k==0)
            return head;
        ListNode curr= head;
        int len=1;
        while (curr.next !=null){
            len++;
            curr=curr.next;
        }
        //reach till that node
        curr.next=head;
        k=k%len;
        k=len-k;
        while(k-->0)curr=curr.next;
        //remove connection
        head=curr.next;
        curr.next=null;
        
        return head;
        
    }
}