[C++ Reminder] LeetCode 2. Add Two Numbers

/**
 * 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* curPtr = new ListNode(0);
        ListNode* ret = curPtr;
        int sum=0, carry = 0;
        while (l1 || l2 || carry) {
            int temp = (l1? l1->val: 0) + (l2? l2->val: 0) + carry;
            curPtr->next = new ListNode(temp%10);
            curPtr = curPtr->next;
            l1 = l1? l1->next: l1;
            l2 = l2? l2->next: l2;
            carry = int(temp/10);            
        }
        return ret->next;
    }
};