Java [leetcode 21]Merge Two Sorted Lists

题目描述：

Merge two sorted linked lists and return it as a new list. The new list should be made by splicing together the nodes of the first two lists.

解题思路：

题目的意思是将两个有序链表合成一个有序链表。

逐个比较加入到新的链表即可。

代码如下：

public static ListNode mergeTwoLists(ListNode l1, ListNode l2) {

		ListNode list = new ListNode(0);

		ListNode tmp = list;

		while (l1 != null || l2 != null) {

			if (l1 == null) {

				tmp.next = new ListNode(l2.val);

				l2 = l2.next;

			} else if (l2 == null) {

				tmp.next = new ListNode(l1.val);

				l1 = l1.next;

			} else {

				if (l1.val < l2.val) {

					tmp.next = new ListNode(l1.val);

					l1 = l1.next;

				} else {

					tmp.next = new ListNode(l2.val);

					l2 = l2.next;

				}

			}

			tmp = tmp.next;

		}

		return list.next;

	}