05. Average Students Grades

package Lekciq;

import java.util.ArrayList;
import java.util.Map;
import java.util.Scanner;
import java.util.TreeMap;

public class AverageStudentsGrades {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);


        int n = scanner.nextInt();
        scanner.nextLine(); // Consume newline

        TreeMap<String, ArrayList<Double>> studentRecords = new TreeMap<>();

        // Reading input and populating student records
        for (int i = 0; i < n; i++) {
            String line = scanner.nextLine();
            String[] parts = line.split(" ");
            String name = parts[0];
            double grade = Double.parseDouble(parts[1]);

            if (!studentRecords.containsKey(name)) {
                studentRecords.put(name, new ArrayList<>());
            }
            studentRecords.get(name).add(grade);
        }

        // Printing grades and average grades for each student
        for (Map.Entry<String, ArrayList<Double>> entry : studentRecords.entrySet()) {
            String name = entry.getKey();
            ArrayList<Double> grades = entry.getValue();
            System.out.print(name + " -> ");
            for (double grade : grades) {
                System.out.printf("%.2f ", grade);
            }
            System.out.printf("(avg: %.2f)\n", calculateAverage(grades));
        }
    }

    // Method to calculate the average grade
    private static double calculateAverage(ArrayList<Double> grades) {
        double sum = 0;
        for (double grade : grades) {
            sum += grade;
        }
        return sum / grades.size();
    }
}