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;
	}