15.合并两个排序的链表

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

    ListNode(int val) {
        this.val = val;
    }
}*/
public class Solution {
    public ListNode Merge(ListNode list1,ListNode list2) {
        if(list1==null){
            return list2;
        }else if(list2==null){
            return list1;
        }
        
        ListNode mergedList=null;
        
        if(list1.val<list2.val){
            mergedList=list1;
            mergedList.next=Merge(list1.next,list2);
        }else{
            mergedList=list2;
            mergedList.next=Merge(list1,list2.next);
        }
        return mergedList;
    }
}