using System;

using System.Collections.Generic;

using System.Diagnostics;

using System.Linq;

​

public class Program

{

    public static void Main()

    {

        var algebra = new Course() { Id = Guid.NewGuid(), Name = "Algebra" };

        var chemistry = new Course() { Id = Guid.NewGuid(), Name = "Chemistry" };

        var english = new Course() { Id = Guid.NewGuid(), Name = "English" };

        var math = new Course() { Id = Guid.NewGuid(), Name = "Math" };

​

        var studentsA = new List<Student>()

        {

            new Student()

            {

                Name = "A1",

                Courses = new List<Course> { algebra, math }

            },

            new Student()

            {

                Name = "A2",

                Courses = new List<Course> { algebra, english }

            },

            new Student()

            {

                Name = "A3",

                Courses = new List<Course> { chemistry, english }

            },

            new Student()

            {

                Name = "A4",

                Courses = new List<Course> { chemistry, english, math }

            },

        };

​

        var studentsB = new List<Student>()

        {

            new Student()

            {

                Name = "B1",

                Courses = new List<Course> { algebra, chemistry }

            },

            new Student()

            {

                Name = "B2",

                Courses = new List<Course> { math, algebra }

            },

            new Student()

            {

                Name = "B3",

                Courses = new List<Course> { math, chemistry, english }

            },

            new Student()

            {

                Name = "B4",

                Courses = new List<Course> { chemistry, english, algebra }

            },

            new Student()

            {

                Name = "B5",

                Courses = new List<Course> { algebra, math }

            },

        };

        var courseBasedStudentMapping = studentsA

            .ToDictionary(

                studentA => studentA,

                studentA => studentsB

                    .Where(studentB => studentB.Courses.Select(course => course.Id).OrderBy(id => id)

                        .SequenceEqual(studentA.Courses.Select(course => course.Id).OrderBy(id => id))));

        foreach (var kvp in courseBasedStudentMapping)

        {

            Console.Write("Student " + kvp.Key.Name + " takes courses: ");

            Console.Write(string.Join(", ", kvp.Key.Courses.Select(course => course.Name)));

            if (kvp.Value.Any())

            {

                Console.Write(" (same as student " + string.Join(", ", kvp.Value.Select(student => student.Name)) + ")");

            }

            Console.WriteLine();

        }

    }

}

​

internal class Student

{

   public Guid Id { get; set; }

   public string Name { get; set; }

   public List<Course> Courses { get; set; } = new();

}

​

internal class Course

{

   public Guid Id { get; set; }

   public string Name { get; set; }

}