1+ //
2+ // Created by DHL on 2022年4月27日.
3+ //
4+ 5+ /* *
6+ * Definition for singly-linked list.
7+ * struct ListNode {
8+ * int val;
9+ * ListNode *next;
10+ * ListNode() : val(0), next(nullptr) {}
11+ * ListNode(int x) : val(x), next(nullptr) {}
12+ * ListNode(int x, ListNode *next) : val(x), next(next) {}
13+ * };
14+ */
15+ class Solution {
16+ public:
17+ ListNode *reverse (ListNode *head) {
18+ ListNode *pre = nullptr ;
19+ while (head) {
20+ ListNode *next = head->next ;
21+ head->next = pre ;
22+ pre = head;
23+ head = next;
24+ }
25+ return pre ;
26+ }
27+ 28+ ListNode *addTwoNumbers (ListNode *l1, ListNode *l2) {
29+ ListNode *p1 = reverse (l1);
30+ ListNode *p2 = reverse (l2);
31+ int carry = 0 ;
32+ ListNode *head = nullptr ;
33+ while ((p1 || p2)) {
34+ int a = p1 ? p1->val : 0 ;
35+ int b = p2 ? p2->val : 0 ;
36+ int sum = a + b + carry;
37+ carry = sum / 10 ;
38+ ListNode *node = new ListNode (sum % 10 );
39+ node->next = head;
40+ head = node;
41+ p1 = p1 ? p1->next : nullptr ;
42+ p2 = p2 ? p2->next : nullptr ;
43+ }
44+ if (carry > 0 ) {
45+ ListNode *node = new ListNode (carry);
46+ node->next = head;
47+ head = node;
48+ }
49+ return head;
50+ }
51+ 52+ };
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