Przykład programu na zaliczenie C#

oceny.cs

using System;
using System.Collections.Generic;
using System.Linq;

// Typy danych
record Student(IEnumerable<SubjectWithMarks> Subjects);

record SubjectWithMarks(Subject Subject, Marks Marks);

record Marks(int Semester1Mark, int Semester2Mark);

enum Subject
{
    Matematyka,
    Historia,
    Chemia
}

// Program

class Program
{
    public static void Main(string[] args)
    {
        // Przykładowi ucznowie i ich oceny:
        var john = new Student(
            new SubjectWithMarks[] {
                new SubjectWithMarks(Subject.Matematyka, new Marks(1, 3)),
                new SubjectWithMarks(Subject.Historia, new Marks(2, 1)),
                new SubjectWithMarks(Subject.Chemia, new Marks(3, 1))
            }
        );

        var andrew = new Student(
            new SubjectWithMarks[] {
                new SubjectWithMarks(Subject.Matematyka, new Marks(2, 2)),
                new SubjectWithMarks(Subject.Historia, new Marks(2, 1)),
                new SubjectWithMarks(Subject.Chemia, new Marks(1, 3))
            }
        );

        var students = new Student[] { john, andrew };

        // Wybór przedmiotu
        var selectedSubject = Subject.Historia;

        // Szukanie przedmiotu
        var semester1Fails = 0;
        var semester2Fails = 0;

        foreach (var student in students)
        {
            var marks = student.Subjects
                .Where(n => n.Subject == selectedSubject)
                .FirstOrDefault()?.Marks;

            semester1Fails += marks?.Semester1Mark == 1 ? 1 : 0;
            semester2Fails += marks?.Semester2Mark == 1 ? 1 : 0;
        }

        // Wyświetlenie informacji
        if (semester1Fails > semester2Fails)
        {
            Console.WriteLine($"Więcej złych ocen z przedmiotu {selectedSubject} w pierwszym semestrze");
        }
        else if (semester1Fails < semester2Fails)
        {
            Console.WriteLine($"Więcej złych ocen z przedmiotu {selectedSubject} w drugim semestrze");
        }
        else
        {
            Console.WriteLine($"Oba semestry mają tę samą ilosć złych ocen z przedmiotu {selectedSubject}");
        }
    }
}