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 mergeHead=null;
if(list1.val<list2.val){
mergeHead=list1;
mergeHead.next=Merge(list1.next, list2);
}
else{
mergeHead=list2;
mergeHead.next=Merge(list1, list2.next);
}
return mergeHead;

}
}