递归的代码真是简洁优美

写递归时：焦点集中在单个节点

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

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