bulbs - facebook code lab - stack overflow, need to work on iterative solution

bulbs1.java

public class Solution {
    public int bulbs(List<Integer> a) {
        if(a == null || a.size() == 0)
        return 0; 
        
        Integer val = a.get(0); 
        a.remove(0); 
        if(val.intValue() ==0)
        {
            List<Integer> opposite = getOpposite(a); 
            return 1 + bulbs(opposite);
        }
        else
            return bulbs(a);
    }
    
    public List<Integer> getOpposite(List<Integer> a)
    {
        List<Integer> list = new ArrayList<Integer>(); 
        if(a== null)
            return list; 
        
        for(int i=0; i< a.size(); i++)
        {
            int val = Integer.valueOf(a.get(i));
            Integer tmp = val == 0? Integer.valueOf(1):Integer.valueOf(0);
            list.add(tmp); 
        }
        
        return list; 
    }
    
}