力扣解题：两顺序链表合并

//方法1、直接链接
//链结点类
public class ListNode {
    int val;
    ListNode next;
    ListNode() {}
    ListNode(int val) { this.val = val; }
    ListNode(int val, ListNode next) { this.val = val; this.next = next; }
}

//实现类
public class lianbiao {
    public ListNode mergeTwoLists(ListNode list1, ListNode list2) {
        ListNode dummy= new ListNode(-1);//哑结点设为dummy,p为dummy的指针
        ListNode p=dummy;

        while(list1!=null&&list2!=null){
            if(list1.val 
public class ListNode {
    int val;
    ListNode next;
    ListNode() {}
    ListNode(int val) { this.val = val; }
    ListNode(int val, ListNode next) { this.val = val; this.next = next; }
}
 
 
public class lianbiao {
    public ListNode mergeTwoLists(ListNode list1, ListNode list2) {
        ListNode dummy= new ListNode(-1);//哑结点设为dummy,p为dummy的指针
        ListNode p=dummy;

        while(list1!=null&&list2!=null){
            if(list1.val