Add Two Numbers

Posted 2022-09-24 tianzeng

You are given two non-empty linked lists representing two non-negative integers. The digits are stored in reverse order and each of their nodes contain a single digit. Add the two numbers and return it as a linked list.

You may assume the two numbers do not contain any leading zero, except the number 0 itself.

Example:

Input: (2 -> 4 -> 3) + (5 -> 6 -> 4)
Output: 7 -> 0 -> 8
Explanation: 342 + 465 = 807.

/**
 * Definition for singly-linked list.
 * struct ListNode 
 *     int val;
 *     ListNode *next;
 *     ListNode(int x) : val(x), next(NULL) 
 * ;
 */
class Solution 
public:
    ListNode* addTwoNumbers(ListNode* l1, ListNode* l2) 
        if(!l1&&!l2)
            return nullptr;
        else if(!l1||!l2)
            return (!l1)?l2:l1;
        
        int carry=0;
        ListNode *res=new ListNode(-1);
        ListNode *t1=l1,*t2=l2,*t=res;
        while(t1||t2||carry)
        
            int num=0;
            if(t1)
                num+=t1->val;
            if(t2)
                num+=t2->val;
            num+=carry;
            
            t->next=new ListNode(num%10);
            carry=num/10;
            
            t=t->next;
            t1=t1?t1->next:nullptr;
            t2=t2?t2->next:nullptr;
        
        ListNode *res1=res->next;
        res->next=nullptr;
        delete res;
        return res1;
    
;