2. 两数相加

问题2 两数相加 ★☆☆☆☆

https://leetcode.cn/problems/add-two-numbers/description/

这个题目本身难度不大，主要考察的是基本的链表操作能力，与合并两个有序链表有一定相似之处。

    public ListNode addTwoNumbers(ListNode l1, ListNode l2) {
        ListNode dummy = new ListNode(-1), tail = dummy;
        int carry = 0;
        while (l1 != null || l2 != null) {
            int val1 = l1 != null ? l1.val : 0;
            int val2 = l2 != null ? l2.val : 0;

            int val = (val1 + val2 + carry) % 10;
            carry = (val1 + val2 + carry) / 10;
            tail.next = new ListNode(val);
            tail = tail.next;

            if (l1 != null) {
                l1 = l1.next;
            }
            if (l2 != null) {
                l2 = l2.next;
            }
        }

        if (carry == 1) {
            tail.next = new ListNode(1);
        }

        return dummy.next;
    }

在 LeetCode 查看