Check divisor , only if it is not visited yet if i is divisor of val , then val / i will be its bigger divisor
if ( t . val % i == 0 && ! st . has ( t . val / i ) ) { q . push ( new data ( t . val / i , t . steps + 1 ) ) ; st . add ( t . val / i ) ; } } } return - 1 ; }