#include "Solution2.hpp"

Solution2::ListNode * Solution2::addTwoNumbers(ListNode *l1, ListNode *l2) {

auto l1_cur = l1;

auto l2_cur = l2;

ListNode *rv = new ListNode{-1};

ListNode *prev = rv;

int carry = 0;

while (l1_cur || l2_cur || carry) {

auto val = (l1_cur ? l1_cur->val : 0) + (l2_cur ? l2_cur->val : 0) + carry;

carry = val / 10;

val = val % 10;

ListNode *node = new ListNode{val};

prev->next = node;

prev = prev->next;

l1_cur = l1_cur ? l1_cur->next : l1_cur;

l2_cur = l2_cur ? l2_cur->next : l2_cur;

}

return rv->next;

}