LeetCode 2. 两数相加(Add Two Numbers)

2. 两数相加

2. Add Two Numbers

题目描述

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.

LeetCode2. Add Two Numbers

Example:

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

Java 实现

class ListNode {
    int val;
    ListNode next;

    ListNode(int x) {
        val = x;
    }

    @Override
    public String toString() {
        return val + "->" + next;
    }
}

class Solution {
    public ListNode addTwoNumbers(ListNode l1, ListNode l2) {
        int carry = 0;
        ListNode newHead = new ListNode(0);
        ListNode p1 = l1, p2 = l2, p3 = newHead;
        while (p1 != null || p2 != null) {
            if (p1 != null) {
                carry += p1.val;
                p1 = p1.next;
            }
            if (p2 != null) {
                carry += p2.val;
                p2 = p2.next;
            }
            p3.next = new ListNode(carry % 10);
            p3 = p3.next;
            carry /= 10;
        }
        if (carry == 1) {
            p3.next = new ListNode(1);
        }
        return newHead.next;
    }
}

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参考资料

• https://leetcode.com/problems/add-two-numbers/
• https://leetcode-cn.com/problems/add-two-numbers/