public class ReverseInteger {
      public static void main(String[] args) {


        System.out.println(reverse(123));
        System.out.println(reverse(-123));

    }

    /**
     *
     * @param number
     * @return
     */

    static int reverse(int number) {
        boolean neg = false ;
        int res = 0 ;

        if( number < 0 ) { neg = true ; number = number * -1; }

        int pos = 1 ;
        while (number > 0) {
            res = res * 10;

            int n = getPosition(number, pos) ;

            number -= n * Math.pow(10, pos - 1 ) ;
            pos ++ ;

            res += n;
        }


        if (neg) return  res * -1 ;


        return res;


    }

    /**
     * the formula (number / 10^(n-1)) % 10 enables us to get
     * number at specific integer
     *
     * @param number the current number
     * @param pos the position of interest
     * @return the integer at specific integer
     */

    static int getPosition(int number, int pos) {
        return (int) ( number / Math.pow(10, pos - 1) % 10);
    }


}