You are given two linked lists representing two non-negative numbers. 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.
Input: (2 -> 4 -> 3) + (5 -> 6 -> 4)
Output: 7 -> 0 -> 8
题意：给两个链表，反向表示两个数，如题干所给两个数分别是342和465，两数相加结果为807，转换成链表为7->0->8
思路：遍历链表，逐位相加，有进位则加标记，在下一次相加是再加标记位。
实现：
/*** Definition for singly-linked list.* public class ListNode {* int val;* ListNode next;* ListNode(int x) {* val = x;* next = null;* }* }*/public class Solution { public ListNode addTwoNumbers(ListNode l1, ListNode l2) { ListNode l=null,front=null,temp=null,i=l1,j=l2; l=new ListNode(0); front=l; int flag=0; while(i!=null||j!=null){ int res=0; if(i==null) res=j.val+flag; else if(j==null) res=i.val+flag; else res=i.val+j.val+flag; if(res<=9){ temp=new ListNode(res); flag=0; } else{ temp=new ListNode(res-10); flag=1; } front.next=temp; front=front.next; if(i==null) j=j.next; else if(j==null) i=i.next; else{ i=i.next; j=j.next; } } if(flag==1){ front.next=new ListNode(1); } return l.next; }}