//直接再链表上操作
class planB{
    public ListNode addTwoNumbers(ListNode l1, ListNode l2) {
        ListNode n1 = l1;
        ListNode n2 = l2;
        int l1Lenth = 0;
        int l2Lenth = 0;
        ListNode temp1 = l1;
        ListNode temp2 = l2;
        ListNode end1 = null;
        ListNode end2 = null;
        while(true){
            if(temp1 == null&&temp2!=null){
                l1Lenth = 0;
                l2Lenth = 1;
                break;
            }
            if(temp1 != null&&temp2==null){
                l1Lenth = 1;
                l2Lenth = 0;
                break;
            }
            if(temp1 == null&&temp2==null){
                l1Lenth = l1Lenth;
                break;
            }
            if(temp1 == null&&temp2==null){
                l1Lenth = l1Lenth;
                break;
            }
            temp1 = temp1.next;
            temp2 = temp2.next;
            }

        //按节点相加,不管进位
        while(true){
            if(n1==null||n2==null){
                break;
            }
            addTwoNodes(n1,n2);
            n1 = n1.next;
            n2 = n2.next;
        }


        n1 = l1;
        n2 = l2;
        //调整长度较长的链表的进位，
        if(l1Lenth>=l2Lenth){//调整长度较长的链表l1的进位，
            while(true){
                if(n1 == null){
                    break;
                }
                else {
                    if(n1.val>=10){
                        if(n1.next !=null) {
                            n1.next.val++;
                        }
                        else{
                            n1.next = new ListNode(1);
                        }
                        n1.val = n1.val-10;
                    }
                }
                n1 = n1.next;
            }
        }
        else{//或者调整长度较长的链表l2的进位，
            while(true){
                if(n2 == null){
                    break;
                }
                else {
                    if(n2.val>=10){
                        if(n2.next !=null) {
                            n2.next.val++;
                        }
                        else{
                            n2.next = new ListNode(1);
                        }
                        n2.val = n2.val-10;
                    }
                }
                n2 = n2.next;
            }
        }
        return l1Lenth>=l2Lenth?l1:l2;

    }

    //遍历较长的链表，在长链表上进行操作,假设n1是较长链表的节点
    public void addTwoNodes(ListNode n1,ListNode n2){
        int sum = n1.val+n2.val;
            n1.val = sum;
            n2.val = sum;
    }

}