剑指Offer(牛客网) 合并两个排序的链表

Posted 2023-01-23

题目来源：

​​https://www.nowcoder.com/practice/d8b6b4358f774294a89de2a6ac4d9337?tpId=13&tqId=11169&tPage=1&rp=1&ru=%2Fta%2Fcoding-interviews&qru=%2Fta%2Fcoding-interviews%2Fquestion-ranking​​

题目描述：

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 class Solution 
    public ListNode Merge(ListNode list1,ListNode list2) 
        if(list1==null)return list2;
        if(list2==null)return list1;
        ListNode head = new ListNode(-1);
        ListNode tail = head;
        while(list1!=null&&list2!=null)
            if(list1.val<=list2.val)
            //list1的值小，就插入list1
                tail.next = list1;
                list1 = list1.next;
            else
               tail.next = list2;
                list2 = list2.next;
            
            tail = tail.next;//尾指针后移
        
        tail.next=  (list1==null?list2:list1);
        return head.next;