TwoSum

 public static ArrayList<Integer> twoSum(List<Integer> a, int target)
  {
    ArrayList<Integer> list = new ArrayList<Integer>();
    HashMap<Integer, Boolean> map = new HashMap<Integer, Boolean>();
    for (Integer i : a)
    {
      int diff = target - i;
      if (map.get(diff) != null)
      {
        list.add(a.indexOf(diff) + 1);
        if (diff != i)
        {
          list.add(a.indexOf(i) + 1);
        }
        else
        {
          for(int num=a.indexOf(diff)+1;num<a.size();num++)
          {
            if(a.get(num)==i)
            {
              list.add(num + 1);
              break;
            }
          }
        }
        break;
      }
      map.put(i, true);
    }
    return list;
  }