力扣题解(链表)

2. 两数相加

/**
 * 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) {
        // 考虑有无进位
        ListNode dummyHead(-1);
        ListNode *p = &dummyHead;
        int t = 0;
        while (l1 || l2 || t != 0) {
            if (l1) {
                t += l1->val;
                l1 = l1->next;
            }
            if (l2) {
                t += l2->val;
                l2 = l2->next;
            }
            p->next = new ListNode(t % 10);
            p = p->next;
            t /= 10;
        }        
        return dummyHead.next;
    }
};