You are given two non-empty linked lists representing two non-negative integers. 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.
You may assume the two numbers do not contain any leading zero, except the number 0 itself.
Input: (2 -> 4 -> 3) + (5 -> 6 -> 4)
Output: 7 -> 0 -> 8
/**
* Definition for singly-linked list.
* public class ListNode {
* int val;
* ListNode next;
* ListNode(int x) { val = x; }
* }
*/
class Solution {
public ListNode addTwoNumbers(ListNode l1, ListNode l2) {
ListNode dummy = new ListNode(0);
ListNode tmp = dummy, i = l1, j = l2;
//carry 進位標志
int carry = 0;
while(i!=null || j != null){
int sum = carry;
// main program 運算
sum += (i != null)? i.val:0;
sum += (j != null)? j.val:0;
// 更新狀態(tài)
tmp.next = new ListNode(sum%10);
tmp = tmp.next;
carry = sum/10;
i = (i == null)?i:i.next;
j = (j==null)?j:j.next;
}
// 最后一位還進位了，需要再添加個node
if (carry !=0){
tmp.next = new ListNode(carry);
}
return dummy.next;
}
}
