链表 ： 指向新创建的节点

tags

linked-list | math

question

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.

myAnswer

• 我的想法是把链表转化成数字，但在java中要考虑数的范围问题，在Python中可行
• 后来室友告诉我，可以链表对应相加，满十进一。

//java
/*** 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) {ListNode unode = new ListNode(0);ListNode ans = unode;int x=0,y=0,flag=0;while ( l1 != null || l2 != null ){ListNode nextnode = new ListNode(0);x = l1 == null ? 0 : l1.val;y = l2 == null ? 0 : l2.val;nextnode.val = (x+y+flag)%10;flag = x+y+flag >= 10 ? 1 : 0;unode.next = nextnode;unode = unode.next;l1 = l1 != null ? l1.next : null;l2 = l2 != null ? l2.next : null;}if(flag == 1){ListNode nextnode = new ListNode(1);unode.next = nextnode;}return ans.next;}
}