LeetCode #2 Add Two Numbers Cpp Solution

LeetCode #2 Problem

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

一个高精度加法的链表实现。

自己的代码太丑，贴个别人的吧。

code from http://blog.csdn.net/feliciafay/article/details/16978487 
class Solution {
public:
ListNode *addTwoNumbers(ListNode *l1, ListNode *l2) {
if((l1==NULL)&&(l2==NULL)) {
return NULL;
}
int sum = 0;
ListNode *root = NULL;
ListNode *tail = NULL;
while(l1 != NULL || l2 != NULL) {
if (l1 != NULL) {
sum += l1->val;
l1 = l1->next;
}
if (l2 != NULL) {
sum += l2->val;
l2 = l2->next;
}
ListNode *p = new ListNode(sum % 10);
if (root == NULL) {
root = p;
tail = p;
} else {
tail->next = p;
tail = p;
}
sum/=10;
}
if (sum != 0) {
ListNode *p = new ListNode(sum % 10);
if (root == NULL) {
root = p;
tail = p;
} else {
tail->next = p;
tail = p;
}
}
return root;
}
};