算法-合并两个有序链表

代码1:
class Solution {
public ListNode mergeTwoLists(ListNode l1, ListNode l2) {
    if(l1==null||l2==null)
        return null; 
    ListNode dummyHead =new ListNode(0);
    ListNode cur = dummyHead;
    while(l1!=null&&l2!=null){
        if(l1.val<=l2.val){
        cur.next=l1;
        cur=cur.next;
        l1=l1.next;
        }else{
       cur.next=l2;
        cur=cur.next;
        l2=l2.next;
        }
    }
    if(l1==null)
        cur.next=l2;
    if(l2==null)
        cur.next=l1;
    return dummyHead.next;

}

}