leetcode

0 class Solution {

1 public:

2 pair<ListNode *, int> reverse(ListNode *root) {

3 ListNode *l = nullptr, *c = root;

4 int size = 0;

5 while (c) {

6 ListNode *n = c->next;

7 c->next = l;

8 l = c;

9 c = n;

10 size++;

11 }

12 return {l, size};

13 }

14

15 ListNode *addTwoNumbers(ListNode *p1, ListNode *p2) {

16 auto [l1, s1] = reverse(p1);

17 auto [l2, s2] = reverse(p2);

18

19 if (s2 > s1) swap(l1, l2);

20 p1 = l1;

21

22 int carry = 0;

23 for (; l1 && l2; l1 = l1->next, l2 = l2->next) {

24 int sum = l1->val + l2->val + carry;

25 l1->val = sum % 10;

26 carry = sum / 10;

27 }

28

29 if (l1) {

30 while (true) {

31 int sum = l1->val + carry;

32 l1->val = sum % 10;

33 carry = sum / 10;

34 if (!l1->next) break;

35 l1 = l1->next;

36 }

37 }

38

39 if (!carry) return reverse(p1).first;

40 return new ListNode(carry, reverse(p1).first);

41 }

42 };