YunheWang0813
10/14/2019 - 9:59 PM

0002. Add Two Numbers

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