LeetCode 002-Add Two Numbers

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

难度：简单

题目分析：两个链表对应的数字相加，关键点在于要考虑进位和两个链表长度不相等的情况

代码：

/**
 * Definition for singly-linked list.
 * public class ListNode {
 *     int val;
 *     ListNode next;
 *     ListNode(int x) { val = x; }
 * }
 */
public class Solution {
    public ListNode addTwoNumbers(ListNode l1, ListNode l2) {
        
    	int tag=0;
    	int value=0;
    	int a=0,b=0;
    	ListNode temp;
    	Queue<ListNode> st=new LinkedList<ListNode>();
    	while(l1!=null||l2!=null||tag!=0){
    		if(l1!=null){
    			a=l1.val;
    		}else{
    			a=0;
    		}
    		if(l2!=null){
    			b=l2.val;
    		}else{
    			b=0;
    		}
    		value=(a+b+tag)%10;
    		tag=(a+b+tag)/10;
    		 temp=new ListNode(value);
    		 st.add(temp);
    		 if(l2!=null){
    			 l2=l2.next; 
    		 }
    		 if(l1!=null){
    			 l1=l1.next;
    		 }
    		
    		 
    	}
    	ListNode result=st.poll();
    	temp=result;
    	while(!st.isEmpty()){
    		temp.next=st.poll();
    		temp=temp.next;
    	}
		return result;
        
    
    }
}