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

两个链表相加的问题，需要处理好进位就成了，比较简单，直接上代码：

  1. class Solution {
  2. public:
  3.     ListNode *addTwoNumbers(ListNode *l1, ListNode *l2) {
  4.         ListNode dummy(0);
  5.         ListNode* p = &dummy;
  7.         int cn = 0;
  9.         while(l1 || l2) {
  10.             int val = cn + (l1 ? l1->val : 0) + (l2 ? l2->val : 0);
  11.             cn = val / 10;
  12.             val = val % 10;
  13.             p->next = new ListNode(val);
  14.             p = p->next;
  15.             if(l1) {
  16.                 l1 = l1->next;
  17.             }
  18.             if(l2) {
  19.                 l2 = l2->next;
  20.             }
  21.         }
  23.         if(cn != 0) {
  24.             p->next = new ListNode(cn);
  25.             p = p->next;
  26.         }
  28.         return dummy.next;
  29.     }
  30. };