DistinctPowers.java

import java.util.ArrayList;

public class DistinctPowers{

    //Check if number exist in array    
    private static boolean isNumberExist(ArrayList<Double> arr, double cmp){
        for(double d: arr){
            if(d == cmp){
                return true;
            }
        }
        return false;
    }

    public static void main(String[] args) throws ParseException{
        int a_min_base = 2;
        int a_max_base = 100;
    
        int b_min_power = 2;
        int b_max_power = 100;
        
        ArrayList<Double> products = new ArrayList<Double>();
    
    
        // compute and popluate array
        for(int base = a_min_base; base <= a_max_base; base++){
            for(int pow = b_min_power; pow <= b_max_power; pow++){
                double prod = Math.pow(base, pow);// compute product
                if(!isNumberExist(products,prod)){ // does number exist?
                    products.add(prod); // push to array
                }
            }
        }
        
        System.out.println(products.size());

    }
}