剑指 Offer 25. 合并两个排序的链表

构造dummyhead 同时遍历俩个链表

  1. public ListNode mergeTwoListsWay2(ListNode l1, ListNode l2) {
  2.         ListNode head = new ListNode(-1);
  3.         ListNode dummyHead = head;
  4.         while (l1!=null&&l2!=null){
  5.             if(l1.val<l2.val){
  6.                 dummyHead.next = l1;
  7.                 l1 = l1.next;
  8.             }else {
  9.                 dummyHead.next = l2;
  10.                 l2 = l2.next;
  11.             }
  12.             dummyHead = dummyHead.next;
  13.         }
  14.         dummyHead.next  = (l1==null?l2:l1);
  15.         return head.next;
  16.     }