Rotate List

Rotate List.java

/*
 * Given a list, rotate the list to the right by k places, where k is non-negative.
 *
 * For example:
 * Given 1->2->3->4->5->NULL and k = 2,
 * return 4->5->1->2->3->NULL.
 */
public class Solution {
    public ListNode rotateRight(ListNode head, int n) {
        // make sure list length > 1
        if (head == null || n == 0 || head.next == null) {
            return head;
        }
        
        ListNode end = head;
        int size = 1;
        
        while (end.next !=  null) {
            end = end.next;
            size ++;
        }
        
        n = n % size;
        if(n == 0) {
            return head;
        }
        
        ListNode connection = head;
        for(int i = 0 ; i< size - n -1; i++) {
            connection = connection.next;
        }
        
        end.next = head;
        head = connection.next;
        connection.next = null;
        return head;

    }
}

// Definition for singly-linked list.
class ListNode {
    int val;
    ListNode next;

    ListNode(int x) {
        val = x;
        next = null;
    }
}