🟡 剑指 Offer II 025. 链表中的两数相加

LeetCode 提示

题目难度 中等

原题链接 🔗 leetcode

题解1

主要是工程问题。用栈来存所有数字，只需遍历两次即可得到结果。

/** * Definition for singly-linked list. * public class ListNode { *     int val; *     ListNode next; *     ListNode() {} *     ListNode(int val) { this.val = val; } *     ListNode(int val, ListNode next) { this.val = val; this.next = next; } * } */class Solution {    public ListNode addTwoNumbers(ListNode l1, ListNode l2) {        Deque<Integer> s1 = new LinkedList<>();        Deque<Integer> s2 = new LinkedList<>();
        while (l1 != null) {            s1.add(l1.val);            l1 = l1.next;        }
        while (l2 != null) {            s2.add(l2.val);            l2 = l2.next;        }
        int up = 0;        ListNode res = null;                while (!s1.isEmpty() || !s2.isEmpty()) {            int cnt = up;            if (!s1.isEmpty()) {                cnt += s1.removeLast();            }            if (!s2.isEmpty()) {                cnt += s2.removeLast();            }
            ListNode cur = new ListNode(cnt % 10, res);            res = cur;            up = cnt / 10;        }
        if (up > 0) {            ListNode cur = new ListNode(up, res);            res = cur;        }
        return res;    }}