LeetCode-Easy刷题(6) Merge Two Sorted Lists

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.

合并两个排序链表，并将其作为一个新列表返回。新的列表应该通过将前两个列表的节点拼接在一起。

  public ListNode mergeTwoLists(ListNode l1, ListNode l2) {        ListNode helper = new ListNode(0);//始终是总表的头部        ListNode pre = helper;//指针控制向前插入 相对参考系l1        pre.next = l1;        while(l1!=null && l2!=null){            if(l1.val>l2.val){                //将l2最前面节点解耦插入链表移动位置指针后                ListNode next = l2.next;                l2.next = pre.next;                pre.next = l2;                l2 = next;            }else{               l1 = l1.next;//移动参考系指针            }            pre = pre.next;        }        if(l2 !=null){            pre.next = l2;        }        return helper.next;    }class ListNode {    int val;    ListNode next;    ListNode(int x) { val = x; }}