21. 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.

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public ListNode mergeTwoLists(ListNode l1, ListNode l2) {    ListNode head = new ListNode(0);    ListNode p = head;    while(l1!=null||l2!=null){        if(l1!=null&&l2!=null){            if(l1.val < l2.val){                p.next = l1;                l1=l1.next;            }else{                p.next=l2;                l2=l2.next;            }            p = p.next;        }else if(l1==null){            p.next = l2;            break;        }else if(l2==null){            p.next = l1;            break;        }    }    return head.next;}