合并排序的思路
class Solution { public ListNode mergeTwoLists(ListNode l1, ListNode l2) { ListNode tem = new ListNode(0); ListNode ans = tem; while(l1!=null&&l2!=null){ if(l1.val<l2.val){ tem.next = l1; l1 = l1.next; } else{ tem.next = l2; l2 = l2.next; } tem = tem.next; } if(l1!=null){tem.next = l1;} if(l2!=null){tem.next = l2;} return ans.next; } }