LeetCode 64 Merge Two Sorted Lists

Merge two sorted linked lists and return it as a new list. The new list should be made by splicing together the nodes of the first two lists.

/** * Definition for singly-linked list. * public class ListNode { *     int val; *     ListNode next; *     ListNode(int x) { *         val = x; *         next = null; *     } * } */public class Solution {    public ListNode mergeTwoLists(ListNode l1, ListNode l2) {        if(l1==null&&l2==null) return null;        ListNode head=new ListNode(-1);        ListNode pNode=head;        while(l1!=null||l2!=null){if(l1==null) {pNode.next=l2;return head.next;}if(l2==null){pNode.next=l1;return head.next;}            if(l1.val>l2.val){pNode.next=l2;l2=l2.next;            }else {pNode.next=l1;l1=l1.next;            }            pNode=pNode.next;                           }        return head.next;    }}