Add two numbers

摘要: Input: (2 -> 4 -> 3) + (5 -> 6 -> 4)
Output: 7 -> 0 -> 8

public ListNode addTwoNumbers(ListNode l1, ListNode l2) {
int carry =0;

ListNode newHead = new ListNode(0);//头结点
ListNode p1 = l1, p2 = l2, p3=newHead;

while(p1 != null || p2 != null){
//10进制进位计算，carry代表进位数，先判断链表是否为空，不为空则取出他的数值，并与另一个链表 //的值相加，如果大于等于10，则当前位为他们的和carry%10,而进位数carry为sum/10
if(p1 != null){
carry += p1.val;
p1 = p1.next;
}

if(p2 != null){
carry += p2.val;
p2 = p2.next;
}
p3.next = new ListNode(carry%10); //存储当前位
p3 = p3.next; //链表增长
carry /= 10;  //进位数
}

if(carry==1)
p3.next=new ListNode(1);

return newHead.next;
}

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.