LintCode_167 链表求和

ListNode *addLists(ListNode *l1, ListNode *l2) {
	// write your code here
    	ListNode* head = NULL;
    	ListNode*p1, *p2, *q, *p;
    	q = head;
    	p1 = l1;
    	p2 = l2;
    	int cp = 0;
    	int t1;
    	int t2;
    	while (p1 || p2)
    	{
    		if (p1)
    		{
    			t1 = p1->val;
    			p1 = p1->next;
    		}
    		else t1 = 0;
    		if (p2)
    		{
    			t2 = p2->val;
    			p2 = p2->next;
    		}
    		else t2 = 0;
    		int sum = t1 + t2 + cp;
    		cp = sum / 10;
    		if (sum >= 10)
    		{
    			sum = sum % 10;
    		}
    		ListNode* p = new ListNode(sum);
    		if (!head) head = q = p;
    		else q = q->next = p;
    	}
    	if (cp)
    	{
    		p = new ListNode(cp);
    		q = q->next = p;
    	}
    	return head;
    }