Ето едно на C#, което може да си адаптираш на Java -> https://pastebin.com/2NBSW9qJ

Здравей,

Изпращам моето решение.

Поздрави

import java.util.Scanner;

public class TestForumQuestionGameOfIntervals {
    public static void main(String[] args) {
        Scanner console = new Scanner(System.in);
        int moves = Integer.parseInt(console.nextLine());

        double score = 0;
        int groupOne = 0;
        int groupTwo = 0;
        int groupThree = 0;
        int groupFour = 0;
        int groupFive = 0;
        int invalidNumbers = 0;

        int counter = 1;
        while(counter <= moves) {
            int number = Integer.parseInt(console.nextLine());

            if (number >= 0 && number <= 9) {
                groupOne++;
                score += number * 0.20;
            } else if (number >= 10 && number <= 19) {
                groupTwo++;
                score += number * 0.30;
            } else if (number >= 20 && number <= 29) {
                groupThree++;
                score += number * 0.40;
            } else if (number >= 30 && number <= 39) {
                groupFour++;
                score += 50;
            } else if (number >= 40 && number <= 50) {
                groupFive++;
                score += 100;
            } else {
                invalidNumbers++;
                score = score / 2;
            }

            counter++;
        }

        double percentageGroupOne = (double)groupOne / moves * 100;
        double percentageGroupTwo = (double) groupTwo / moves * 100;
        double percentageGroupThree = (double) groupThree / moves * 100;
        double percentageGroupFour = (double) groupFour / moves * 100;
        double percentageGroupFive = (double) groupFive / moves * 100;
        double percentageInvalidNumbers = (double) invalidNumbers / moves * 100;

        System.out.printf("%.2f%n", score);
        System.out.printf("From 0 to 9: %.2f%%%n", percentageGroupOne);
        System.out.printf("From 10 to 19: %.2f%%%n", percentageGroupTwo);
        System.out.printf("From 20 to 29: %.2f%%%n", percentageGroupThree);
        System.out.printf("From 30 to 39: %.2f%%%n", percentageGroupFour);
        System.out.printf("From 40 to 50: %.2f%%%n", percentageGroupFive);
        System.out.printf("Invalid numbers: %.2f%%%n", percentageInvalidNumbers);
    }
}