题目:

输入两个单调递增的链表，输出两个链表合成后的链表，当然我们需要合成后的链表满足单调不减规则。

public static  ListNode Merge(ListNode list1, ListNode list2) {
       if (list1 == null) {
           return list2;
       }
       if (list2 == null) {
           return list1;
       }
       if (list1 == null && list2 == null) {
           return null;
       }
       List<ListNode> list = new ArrayList<>();
       ListNode cur1 = list1;
       ListNode cur2 = list2;
       while (cur1 != null || cur2 != null) {
           if(cur1 == null){
               list.add(cur2);
               cur2 = cur2.next;
               continue;
           }
           if(cur2 == null){
               list.add(cur1);
               cur1 = cur1.next;
               continue;
           }
           if (cur1.val < cur2.val) {
               list.add(cur1);
               cur1 = cur1.next;
               continue;
           }
           if (cur1.val >= cur2.val) {
               list.add(cur2);
               cur2 = cur2.next;
               continue;
           }
       }
       for (int i = 0; i < list.size() - 1; i++) {
           list.get(i).next = list.get(i + 1);
       }
       return list.get(0);
   }