Add Two Numbers

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Add Two Numbers

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

需要考虑的情况比较多，考虑全了就好~

代码如下：（代码有待改进）

/** * Definition for singly-linked list. * struct ListNode { *     int val; *     ListNode *next; *     ListNode(int x) : val(x), next(NULL) {} * }; */class Solution {public:    int getLength(ListNode* head)  //get the length of list    {        if(head==NULL)        {            return 0;         }        int length=0;         ListNode* p=head;         while(p)        {            length++;             p=p->next;         }        return length;     }        ListNode* fun(ListNode *l1, ListNode *l2)     {        ListNode *p=l1;        ListNode *q=l2;        ListNode *r=p;        bool flag=false;        while(q)        {            r=p;            if(flag)            {                p->val+=q->val+1;                flag=false;            }            else                p->val+=q->val;            if(p->val>9)            {                flag=true;                p->val=p->val%10;            }            p=p->next;            q=q->next;        }        while(flag)        {            if(!p)            {                ListNode *newnode=new ListNode(1);                r->next=newnode;                flag=false;            }            else            {                p->val+=1;                flag=false;                if(p->val>9)                {                    flag=true;                    p->val=p->val%10;                    r=p;                    p=p->next;                }            }        }        return l1;    }        ListNode *addTwoNumbers(ListNode *l1, ListNode *l2) {                int len1=getLength(l1);         int len2=getLength(l2);                 if(len1==0)        {            return l2;         }        else if(len2==0)        {            return l1;         }        else if(len1<len2)        {            return fun(l2, l1);         }        else         {            return fun(l1, l2);         }            }};

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