package leetcode.easy;

/**

 * Definition for singly-linked list. public class ListNode { int val; ListNode

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

 */

public class ReverseLinkedList {

	private static void print(ListNode head) {

		if (head == null) {

			return;

		}

		while (head != null) {

			System.out.print(head.val);

			if (head.next != null) {

				System.out.print("->");

			}

			head = head.next;

		}

		System.out.println("->NULL");

	}

	public ListNode reverseList(ListNode head) {

		ListNode nextNode = null;

		ListNode curr = head;

		while (curr != null) {

			ListNode tempNext = curr.next;

			curr.next = nextNode;

			nextNode = curr;

			curr = tempNext;

		}

		return nextNode;

	}

	@org.junit.Test

	public void test() {

		ListNode ln1 = new ListNode(1);

		ListNode ln2 = new ListNode(2);

		ListNode ln3 = new ListNode(3);

		ListNode ln4 = new ListNode(4);

		ListNode ln5 = new ListNode(5);

		ln1.next = ln2;

		ln2.next = ln3;

		ln3.next = ln4;

		ln4.next = ln5;

		ln5.next = null;

		print(ln1);

		print(reverseList(ln1));

	}

}