https://programmingpraxis.com/2016/04/05/java-interview-question/

Grade.java

import static java.lang.Integer.parseInt;
import static java.util.Comparator.comparing;
import static java.util.stream.Collectors.collectingAndThen;
import static java.util.stream.Collectors.minBy;

import java.io.IOException;
import java.nio.file.Files;
import java.nio.file.Paths;
import java.util.Map;
import java.util.Optional;
import java.util.function.BiFunction;
import java.util.function.Function;

public record Grade(int studentID, String courseTitle, int score) {
    public Grade(String record) {
        String[] values = record.split("\\|");
        this(parseInt(values[0]), values[1], parseInt(values[2]));
    }
    
    private static <T, K, V, R> Collector<T, ?, Stream<R>> groupingByAndMapping(
        Function<? super T, ? extends K> key,
        Collector<? super T, ?, Optional<V>> values,
        BiFunction<? super K, ? super V, ? extends R> function
    ) {
        return collectingAndThen(
            groupingBy(key, values),
            map -> map.entrySet().stream.flatMap(
                entry -> entry.getValue().map(value -> function.apply(entry.getKey(), value)).stream()
            )
        );
    }

    public static void main(String[] args) throws IOException {
        Files.lines(Paths.get(args[0])).map(Grade::new).collect(
            groupingByAndMapping(
                Grade::courseTitle,
                minBy(comparing(Grade::studentID)),
                (courseTitle, grade) -> "%s %d%".formatted(courseTitle, grade.score())
            )
        ).forEach(System.out::println);
    }
}