leetcode Add Two Numbers

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
做leetcode也一段时间了，感觉leetcode的题有很多都说的不清不楚，需要自己去挖掘，比如这题，两数相加的结果是要求余的，而大于10的数需要/10后添加到下一组数据中.这道题比较水，就是逐个遍历，通过变量sum去记录两者相加的结果，然后做求余等处理。
代码没什么难度，明白题意很容易写出来。

ListNode *addTwoNumbers(ListNode *l1, ListNode *l2) {
ListNode *p = new ListNode(0);
ListNode *head = p;
int sum = 0;
while(l1 || l2){
if(l1){
sum += l1 -> val;
l1 = l1 -> next;
}
if(l2){
sum += l2 -> val;
l2 = l2 -> next;
}
p -> next = new ListNode(sum % 10);
p = p -> next;
sum /= 10;
}
if(sum)
p -> next = new ListNode(sum);
return head -> next;
}