using System;

using System.Collections.Generic;

using System.Linq;

​

public class Program

{

    public static void Main()

    {

        var list = new List<DegreeResponse>()

        {

            new DegreeResponse() { Code = "1", Period = "2/2/2020" },

            new DegreeResponse() { Code = "1", Period = "2/5/2020" },

            new DegreeResponse() { Code = "1", Period = "2/8/2020" },

            new DegreeResponse() { Code = "1", Period = "2/11/2020" },

            new DegreeResponse() { Code = "1", Period = "2/2/2021" },

            new DegreeResponse() { Code = "1", Period = "2/2/2021" },

            new DegreeResponse() { Code = "2", Period = "2/2/2021" },

            new DegreeResponse() { Code = "2", Period = "2/2/2021" },

        };

​

        var distinctedByCode = list.Distinct(new DegreeComparer()).ToList();

        Console.WriteLine("" + distinctedByCode.Count);

    }

    public class DegreeResponse {

      public string Code { get ;set;}

        public string Period {get;set;}

    }

    // Custom comparer for the Product class

    class DegreeComparer : IEqualityComparer<DegreeResponse>

    {

        // Products are equal if their names and product numbers are equal.

        public bool Equals(DegreeResponse x, DegreeResponse y)

        {

​

            //Check whether the compared objects reference the same data.

            if (Object.ReferenceEquals(x, y)) return true;

​

            //Check whether any of the compared objects is null.

            if (Object.ReferenceEquals(x, null) || Object.ReferenceEquals(y, null))

                return false;

​

            //Check whether the products' properties are equal.

            return x.Code == y.Code && x.Period == y.Period;

        }

​

        // If Equals() returns true for a pair of objects

        // then GetHashCode() must return the same value for these objects.

​

        public int GetHashCode(DegreeResponse d)

        {

            //Check whether the object is null

            if (Object.ReferenceEquals(d, null)) return 0;

​

            //Get hash code for the Code field if it is not null.

            int hashProductCode = d.Code == null ? 0 : d.Code.GetHashCode();

            return hashProductCode;

​

            //Get hash code for the Period field.

            // int hashProductPeriod = d.Period.GetHashCode();

​

            //Calculate the hash code for the degree.

            // return hashProductCode ^ hashProductPeriod;

        }

    }

}