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程式語言 - LeetCode - C++ - 445. Add Two Numbers II

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題目：


解答：

/**
 * Definition for singly-linked list.
 * struct ListNode {
 *     int val;
 *     ListNode *next;
 *     ListNode() : val(0), next(nullptr) {}
 *     ListNode(int x) : val(x), next(nullptr) {}
 *     ListNode(int x, ListNode *next) : val(x), next(next) {}
 * };
 */
class Solution {
public:
    ListNode* addTwoNumbers(ListNode* l1, ListNode* l2) {
        stack<int> s1;
        stack<int> s2;

        while (l1) {
            s1.push(l1->val);
            l1 = l1->next;
        }

        while (l2) {
            s2.push(l2->val);
            l2 = l2->next;
        }

        int c = 0;
        ListNode *head = nullptr;

        while (!s1.empty() || !s2.empty() || c) {
            int sum = c;

            if (!s1.empty()) {
                sum += s1.top();
                s1.pop();
            }

            if (!s2.empty()) {
                sum += s2.top();
                s2.pop();
            }

            c = sum / 10;
            ListNode *cur = new ListNode(sum % 10);
            cur->next = head;
            head = cur;
        }

        return head;
    }
};