牛客网--合并两个排序的链表

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。

代码

/*
public class ListNode {
    int val;
    ListNode next = null;

    ListNode(int val) {
        this.val = val;
    }
}*/
public class Solution {
    public ListNode Merge(ListNode list1,ListNode list2) {
        ListNode head = new ListNode(-1);
        ListNode pHead = head;
        while(list1 != null && list2 != null)
        {
            if(list1.val <= list2.val)
            {
                head.next = list1;
                head = list1;
                list1 = list1.next;
            }
            else
            {
                head.next = list2;
                head = list2;
                list2 = list2.next;
            }
        }
        if(list1 != null)
        {
            head.next = list1;
        }
        if(list2 != null)
        {
            head.next = list2;
        }
        return pHead.next;
    }
}