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;
}
Java [leetcode 21]Merge Two Sorted Lists
原文：http://www.cnblogs.com/zihaowang/p/4492969.html