LeetCode 2. Add Two Numbers

最新推荐文章于 2025-09-07 01:02:55 发布

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最新推荐文章于 2025-09-07 01:02:55 发布

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原文链接：https://my.oschina.net/u/3706181/blog/1593298

本文提供了一种解决LeetCode上经典题目“两数相加”的算法思路及实现。该题要求将两个以链表形式逆序存储的非负整数相加，并返回结果链表。文中给出了具体的解决方案，通过遍历两个链表节点，逐位相加并处理进位。

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Link

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

Description

You are given two non-empty linked lists representing two non-negative integers. The digits are stored in reverse order and each of their nodes contain a single digit. Add the two numbers and return it as a linked list.

You may assume the two numbers do not contain any leading zero, except the number 0 itself.

Example

Input: (2 -> 4 -> 3) + (5 -> 6 -> 4)
Output: 7 -> 0 -> 8
Explanation: 342 + 465 = 807.

Solution

/**
 * Definition for singly-linked list.
 * public class ListNode {
 *     int val;
 *     ListNode next;
 *     ListNode(int x) { val = x; }
 * }
 */
class Solution {
    
    public ListNode addTwoNumbers(ListNode l1, ListNode l2) {

        if (l1 == null && l2 == null) {
            return null;
        }

        boolean isBiggerThan10 = false;
        int val = 0;
        ListNode listNode = new ListNode(0);

        ListNode nextNode = listNode;

        while (l1 != null || l2 != null || isBiggerThan10) {
            val = (l1 == null ? 0 : l1.val) + (l2 == null ? 0 : l2.val) + (isBiggerThan10 ? 1 : 0);
            nextNode.next = new ListNode(val%10);
            isBiggerThan10 = val / 10 >= 1;
            nextNode = nextNode.next;

            l1 = (l1 == null)? null:l1.next;
            l2 = (l2 == null)? null:l2.next;
        }

        return listNode.next;

    }

}

TestCase

Input: (5) + (5)
Output: 0 -> 1

Input: (1) + (9 -> 9)
Output: 0 -> 0 -> 1

转载于:https://my.oschina.net/u/3706181/blog/1593298