2.两数相加

class Solution {
public:
    ListNode* addTwoNumbers(ListNode* l1, ListNode* l2) {
        ListNode* h = new ListNode(0),
            *nh = h;
        int add = 0;
        while(l1 && l2) {
            int val = l1->val + l2->val + add;
            nh->next = new ListNode(val % 10);
            add = val / 10;
            l1 = l1->next;
            l2 = l2->next;
            nh = nh->next;
        }
        if(!l1)
            l1 = l2;
        while(l1) {
            int val = l1->val + add;
            nh->next = new ListNode(val % 10);
            add = val / 10;
            l1 = l1->next;
            nh = nh->next;
        }
        if(add) 
            nh->next = new ListNode(add);
        return h->next;
    }
};

Accepted

1563/1563 cases passed (24 ms)

Your runtime beats 72.27 % of cpp submissions

Your memory usage beats 5.26 % of cpp submissions (10.5 MB)