Задача 3

import java.util.ArrayList;
import java.util.Comparator;

public class homеwork3 {
    public static void main(String[] args) {

        ArrayList<Integer> nz1 = new ArrayList<>();
        int[] arr = {5,14,9,17, 81};
        for (int i = 0; i < arr.length; i++) {
            for (int j = 0; j <= arr[i]/2; j++) {
                if (j * j == arr[i]){
                    nz1.add(arr[i]);
                }
            }
        }
       nz1.sort(Comparator.reverseOrder());

        System.out.println(nz1);
    }
}