LeetCode-Easy刷题 Merge Two Sorted Lists

Posted 2022-05-31 当以乐

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;