每日一題（day2）

Leetcode002

Add Two Numbers問題
知識更新：鏈表結構

    ListNode* addTwoNumbers(ListNode* l1, ListNode* l2) {
        int carry = 0;
        int sum = 0;
        ListNode* res = new ListNode(-1);
        ListNode* cur = res;
        ListNode* pl1 = l1;
        ListNode* pl2 = l2;
        while (1)
        {
            if (pl1&&pl2)
            {
                sum = pl1->val + pl2->val + carry;
                cur->next = new ListNode(sum % 10);
                carry = sum / 10;
                cur = cur->next;
                pl1 = pl1->next;
                pl2 = pl2->next;
                continue;
            }
            if (pl1)
            {
                sum = pl1->val + carry;
                cur->next = new ListNode(sum % 10);
                carry = sum / 10;
                cur = cur->next;
                pl1 = pl1->next;
                continue;
            }
            if (pl2)
            {
                sum = pl2->val + carry;
                cur->next = new ListNode(sum % 10);
                carry = sum / 10;
                cur = cur->next;
                pl2 = pl2->next;
                continue;
            }
            if (carry)
                cur->next = new ListNode(carry);
            break;
        }
        ListNode* temp = res->next;
        delete res;
        return temp;
    }

注意問題：鏈表首位置以及新節點創建