For Riddler Express Challenge from 538

SmallestDenominator.java

public class SmallestDenominator {

    public static void main(String[] args) {
        double min_denominator = 1000000000;
        double numerator = 0;
        for(double i=1;i<100000;i++){
            for(double j=1;j<50000;j++){
                if(((double)1/2019 > i/j) && (i/j > (double)1/2020)){
                    if(j<min_denominator){
                        min_denominator = j;
                        numerator = i;
                    }
                }
            }
        }
        System.out.println("Smallest denominator: " + min_denominator);
        System.out.println("Numerator for smallest denominator: " + numerator);
    }
}

This value is between 1/2019 and 1/2020.

Output:

Smallest denominator: 4039.0
Numerator for smallest denominator: 2.0