Nth to Last Node in List

Find the nth to last element of a singly linked list. 

The minimum number of nodes in list is n.

Have you met this question in a real interview?

Yes

Example

Given a List  3->2->1->5->null and n = 2, return node  whose value is 1.

/**

 * Definition for ListNode.

 * public class ListNode {

 *     int val;

 *     ListNode next;

 *     ListNode(int val) {

 *         this.val = val;

 *         this.next = null;

 *     }

 * }

 */ 

public class Solution {

    /**

     * @param head: The first node of linked list.

     * @param n: An integer.

     * @return: Nth to last node of a singly linked list. 

     */

    ListNode nthToLast(ListNode head, int n) {

        // write your code here

        if(head == null || n <= 0) return head;

        ListNode node = head;

       int count = 0;

        while(node != null && count < n){

            count++;

            node = node.next;

        }

        while(node != null){

            head = head.next;

            node = node.next;

        }

        return head;

    }

}