cs-notes/面试高频题/0002 两数相加.cpp at master · Hansimov/cs-notes · GitHub

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/**
 * 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) {
        ListNode *dummy = new ListNode(-1);
        ListNode *p = dummy;
        int sum = 0;
        int carry = 0;
        while (l1 || l2) {
            sum = 0;
            if (l1) {
                sum += l1->val;
                l1 = l1->next;
            }
            if (l2) {
                sum += l2->val;
                l2 = l2->next;
            }
            sum += carry;
            carry = sum / 10;
            p->next = new ListNode(sum % 10);
            p = p->next;
        }
        if (carry>0)
            p->next = new ListNode(1);
        return dummy->next;
    }
};