leetcode 2 Add Two Numbers

问题

代码(36ms)

/**
* 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) {
int over = 0;
int add = 0;
ListNode * head = new ListNode(0);
ListNode * now = head;
while(l1||l2){
if (l1 && l2)
{
add = l1->val + l2->val + over;

l1 = l1->next;
l2= l2->next;
}
else{
if (l1)
{
add = l1->val + over;
l1 = l1->next;
}else// l2;
{
add = l2->val + over;
l2 = l2->next;
}
}
over = add / 10;
add = add %10;
now->next = new ListNode(add);
// 指向 下一个位置。。
now = now->next;
}
if (over)
{
now->next = new ListNode(over);
}

if (head->next != NULL)// 说明result链表有长度，
{
now = head;
head = head->next;
delete now;
}
return head;
}
};