167 · Add Two Numbers - LintCode

# Description

You have two numbers represented by a linked list, where each node contains a single digit. The digits are stored in reverse order, such that the 1's digit is at the head of the list. Write a function that adds the two numbers and returns the sum as a linked list.
Example 1:

Input: 7->1->6->null, 5->9->2->null
Output: 2->1->9->null	
Explanation: 617 + 295 = 912, 912 to list:  2->1->9->null

Example 2:

Input:  3->1->5->null, 5->9->2->null
Output: 8->0->8->null	
Explanation: 513 + 295 = 808, 808 to list: 8->0->8->null

# Solution

a

	/**
	* Definition for ListNode
	* public class ListNode {
	* int val;
	* ListNode next;
	* ListNode(int x) {
	* val = x;
	* next = null;
	* }
	* }
	*/

	public class Solution {
	/**
	* @param l1: the first list
	* @param l2: the second list
	* @return: the sum list of l1 and l2
	*/
	public ListNode addLists(ListNode l1, ListNode l2) {
	if (l1 == null \|\| l2 == null){
	return null;
	}

	ListNode head = new ListNode(0);
	ListNode point = head;
	int carry = 0;
	while (l1 != null && l2 != null){
	int sum = carry + l1.val + l2.val;
	point.next = new ListNode(sum % 10); //12%10 記 2
	carry = sum / 10; //carry = 1;
	point = point.next;
	l1 = l1.next;
	l2 = l2.next;
	}
	while (l2 != null){
	int sum = carry + l2.val;
	point.next = new ListNode(sum % 10);
	carry = sum / 10; //carry = 1;
	point = point.next;
	l2 = l2.next;

	}
	while (l1 != null){
	int sum = carry + l1.val;
	point.next = new ListNode(sum % 10);
	carry = sum / 10; //carry = 1;
	point = point.next;
	l1 = l1.next;

	}

	if (carry != 0) {
	point.next = new ListNode(carry);
	}
	return head.next;

	}
	}