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/**
 * Definition for singly-linked list.
 * struct ListNode {
 *     int val;
 *     ListNode *next;
 *     ListNode() : val(0), next(nullptr) {}
 *     ListNode(int x) : val(x), next(nullptr) {}
 *     ListNode(int x, ListNode *next) : val(x), next(next) {}
 * };
 */
class Solution {
public:
    ListNode* addTwoNumbers(ListNode* l1, ListNode* l2) {
        ListNode* result ,*current= new ListNode(),*ln1=l1,*ln2=l2;
        int carrier = 0,sum=0;
        result=current;
        current->next=NULL;
        while (ln1 != nullptr || ln2 !=nullptr || carrier != 0){
            ListNode* resNext = new ListNode();
            if(ln1 != nullptr && ln2!= nullptr){
                sum = ln1->val + ln2->val+carrier;    
            }
            else if (ln1 == nullptr && ln2== nullptr) sum = carrier;
            else if  (ln1 == nullptr ){
                sum = ln2->val+carrier;    
            }
            else{
                sum = ln1->val + carrier;    
            }
            carrier = sum/10;
            current->val = sum%10;
            current->next = resNext;
            current = current->next ;
            ln1 = ln1->next;
            ln2 = ln2->next;
            cout<<result->next<<endl;
            
        }
        
        ListNode* dummy = result;
        while(dummy != nullptr){
            cout<<dummy->val<<endl;
            dummy = dummy->next;
        }
        return result;
    }
};