JSON to Array Data

I know that what i want is something like this

PHP Code:

[enrollID[1515]] => 29
    [basic_salary[1515]] => 34500
    [allowance[1515][16]] => 0

 change to 
   enrollID => array(
     1515 => 29,
), 
basic_salary => array(
  1515 => 34500,
),

allowance => array(
    1515 => array(
        16 => 0
    )
)