题解 | #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&&list2==null) return list1;
        if(list1==null) return list2;
        if(list2==null) return list1;

        ListNode dummy = new ListNode(-1);
        if(list1.val<list2.val){
            dummy.next = list1;
            list1 = list1.next;
        }else{
            dummy.next = list2;
            list2 = list2.next;
        }
        ListNode cur = dummy.next;
        while(list1!=null&&list2!=null){
            if(list1.val<list2.val){
                cur.next = list1;
                list1 = list1.next;
            }else{
                cur.next = list2;
                list2 = list2.next;
            }
            cur = cur.next;
        }
        if(list1==null) cur.next = list2;
        if(list2==null) cur.next = list1;
        return dummy.next;
    }
}