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.
Input: (2 -> 4 -> 3) + (5 -> 6 -> 4) Output: 7 -> 0 -> 8
思路：将两个链表对应指针位置的数字相加，注意进位。
/** * Definition for singly-linked list. * struct ListNode { * int val; * ListNode *next; * ListNode(int x) : val(x), next(NULL) {} * }; */ class Solution { public: ListNode* addTwoNumbers(ListNode* l1, ListNode* l2) { ListNode *head=new ListNode(0); ListNode *ptr=head; int carry=0; while(true) { if(l1!=NULL) { carry+=l1->val; l1=l1->next; } if(l2!=NULL) { carry+=l2->val; l2=l2->next; } ptr->val=carry%10; carry/=10; if(l1!=NULL||l2!=NULL||carry!=0) { ptr->next=new ListNode(0); ptr=ptr->next; } else break; } return head; } };