Add Two Numbers Leetcode 鏈表相加

</pre><pre name="code" class="java">

import java.util.List;

/**
 * Created by Cookies on 2015-01-04.
 * 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
 */
public class AddTwoNumbers {
    public static void main(String[] args){
        ListNode node1 = new ListNode(9);
        ListNode node2 = new ListNode(9);
        ListNode node3 = new ListNode(9);
        ListNode node4 = new ListNode(9);

        node1.next = node2;
        node3.next = node4;

        addTwoNumbers(node1,node3);
    }

    public static ListNode addTwoNumbers(ListNode l1,ListNode l2){
        if (l1==null && l2==null) return null;

        if(l1==null || l2 == null){
            return l1==null?l2:l1;
        }

        int addTemp = 0;
        int addUp = 0;

        addTemp = l1.val+l2.val;
        addUp = addTemp/10;
        ListNode head = new ListNode(addTemp%10);
        ListNode tempNode = head;
        l1 = l1.next;
        l2 = l2.next;

        while (l1!=null && l2!=null){
            addTemp = l1.val+l2.val+addUp;
            addUp = addTemp/10;
            ListNode tempNode2 = new ListNode(addTemp%10);
            tempNode.next=tempNode2;

            l1 = l1.next;
            l2 = l2.next;
            tempNode = tempNode.next;
        }

        while (l1 !=null){
            addTemp = l1.val+addUp;
            addUp = addTemp/10;
            ListNode tempNode2 = new ListNode(addTemp%10);
            tempNode.next=tempNode2;

            l1 = l1.next;
            tempNode=tempNode.next;
        }

        while (l2 !=null){
            addTemp = l2.val+addUp;
            addUp = addTemp/10;
            ListNode tempNode2 = new ListNode(addTemp%10);
            tempNode.next=tempNode2;

            l2 = l2.next;
            tempNode=tempNode.next;
        }

        if(addUp>0){
            ListNode nodeTemp = new ListNode(addUp);
            tempNode.next = nodeTemp;
        }

        return head;
    }
}