题目：
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.
思路：
不断选取较小的元素，当一个链表为空时，则直接链接到下一个链表。
package list; public class MergeTwoSortedLists { public ListNode mergeTwoLists(ListNode l1, ListNode l2) { ListNode p = new ListNode(0); p.next = null; ListNode head = p; while (l1 != null && l2 != null) { if (l1.val < l2.val) { p.next = l1; l1 = l1.next; } else { p.next = l2; l2 = l2.next; } p = p.next; } p.next = l1 == null ? l2 : l1; return head.next; } public static void main(String[] args) { // TODO Auto-generated method stub } }