[LeetCode#2][C]Add Two Numbers

/**
* Definition for singly-linked list.
* struct ListNode {
*     int val;
*     struct ListNode *next;
* };
*/
struct ListNode* addTwoNumbers(struct ListNode* l1, struct ListNode* l2) {
struct ListNode* l3=(struct ListNode*)malloc(sizeof(struct ListNode));
struct ListNode* cur=l3;             //指向当前结点
int carry=0;                         //进位
while(l1!=NULL||l2!=NULL)
{
int sum=0,a,b;
a=(l1!=NULL)?l1->val:0;
b=(l2!=NULL)?l2->val:0;
sum=a+b+carry;
carry=sum/10;
cur->next=(struct ListNode*)malloc(sizeof(struct ListNode));
cur=cur->next;
cur->val=sum%10;
if(l1!=NULL)
l1=l1->next;
if(l2!=NULL)
l2=l2->next;
}
if(carry>0)                        //链表结束后是否还有进位
{
cur->next=(struct ListNode*)malloc(sizeof(struct ListNode));
cur=cur->next;
cur->val=carry;
}
cur->next=NULL;                   //注意细节
return l3->next;
}