java simple solution


  • 0
    T
        public ListNode mergeTwoLists(ListNode l1, ListNode l2) {
            if(l1==null) return l2;
            if(l2==null) return l1;
            ListNode head = new ListNode(0);
            ListNode tail = new ListNode(0);
            if(l1.val<l2.val){
                head = l1;
                l1 = l1.next;
                tail = head;
            }
            else{
                head = l2;
                l2 = l2.next;
                tail = head;
            }
            while(l1!=null || l2!=null){
                if(l1==null){
                    tail.next = l2;
                    tail = tail.next;
                    l2 = l2.next;
                }else if(l2==null){
                    tail.next = l1;
                    tail = tail.next;
                    l1 = l1.next;
                }else if(l1.val<l2.val){
                    tail.next = l1;
                    tail = tail.next;
                    l1 = l1.next;
                }else{
                    tail.next = l2;
                    tail = tail.next;
                    l2 = l2.next;
                }
            }
            return head;
        }
    }```

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