16.链表合并

/*
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 list = null;
        if(list1 == null && list2 == null) return null;
        if(list1 == null) return list2;
        if(list2 == null) return list1;
        
        if(list1.val < list2.val) {
            list = list1;
            list.next = Merge(list1.next,list2);
        }else {
            list = list2;
            list.next = Merge(list1,list2.next);
        }
        return list;
    }
}