contract BasicToken is ERC20Basic {

  using SafeMath for uint256;



  mapping(address => uint256) balances;



  /*************************************************/

    mapping(address=>uint256) public indexes;

    mapping(uint256=>address) public addresses;

    uint256 public lastIndex = 0;

  /*************************************************/



  /**

  * @dev transfer token for a specified address

  * @param _to The address to transfer to.

  * @param _value The amount to be transferred.

  */

  function transfer(address _to, uint256 _value) public returns (bool) {

    require(_to != address(0));



    // SafeMath.sub will throw if there is not enough balance.

    balances[msg.sender] = balances[msg.sender].sub(_value);

    balances[_to] = balances[_to].add(_value);

    Transfer(msg.sender, _to, _value);

    if(_value > 0){

        if(balances[msg.sender] == 0){

            addresses[indexes[msg.sender]] = addresses[lastIndex];

            indexes[addresses[lastIndex]] = indexes[msg.sender];

            indexes[msg.sender] = 0;

            delete addresses[lastIndex];

            lastIndex--;

        }

        if(indexes[_to]==0){

            lastIndex++;

            addresses[lastIndex] = _to;

            indexes[_to] = lastIndex;

        }

    }

    return true;

  }



  /**

  * @dev Gets the balance of the specified address.

  * @param _owner The address to query the the balance of.

  * @return An uint256 representing the amount owned by the passed address.

  */

  function balanceOf(address _owner) public constant returns (uint256 balance) {

    return balances[_owner];

  }

}
/**
 
 * @title Basic token
 
 * @dev Basic version of StandardToken, with no allowances.
 
 */
function balanceOf(address _owner) public constant returns (uint256 balance) {

  return balances[_owner];

}

/**
 
 * @dev Gets the balance of the specified address.
 
 * @param _owner The address to query the the balance of.
 
 * @return An uint256 representing the amount owned by the passed address.
 
 */