using System;

using System.Collections.Generic;

​

public class Program

{

    public static void Main()

    {

        var service = new EntityService();

        service.EnsureChildRecords(100);

        service.EnsureChildRecords(200);

        var expected = 10;

        var childCount = service.GetChildRecords(100).Count;

        Console.WriteLine(childCount == expected ? "PASS" : "FAIL, child count is " + childCount);

        childCount = service.GetChildRecords(200).Count;

        Console.WriteLine(childCount == expected ? "PASS" : "FAIL, child count is " + childCount);

    }

}

​

// INSTRUCTIONS:

// We have a backend operation that adds 7 Child records to most entities; some entities

// have no Child records.  We are now adding functionality that requires certain entities

// to have no fewer than 10 Child records.

// Flesh out EnsureChildRecords() so that it makes sure the specified entity has at least

// 10 Child records.  Assume CreateChildRecord() performs whatever work is necessary to

// add the record to the database.  Both tests in Main() should PASS.

public class EntityService

{

    Dictionary<int, List<Child>> db = new Dictionary<int, List<Child>>();

    public EntityService()

    {

        // Initialize the fake database

        db.Add(100, new List<Child>());

        for (int a = 0; a < 7; a++)

            CreateChildRecord(100);

        db.Add(200, new List<Child>());

    }

​

    public void EnsureChildRecords(int entityId)

    {

        var existingRecords = GetChildRecords(entityId);

        // Your code:

        var expected = 10;

        var diff = expected - existingRecords.Count;

        if (diff < 11)

            for (int a = 0; a < diff; a++)

            {

                CreateChildRecord(entityId);

            }

    }

​

    // ***** No need to modify anything below this point *****

    private void CreateChildRecord(int entityId)

    {

        db[entityId].Add(new Child());

    }

​

    public List<Child> GetChildRecords(int entityId)

    {

        return db[entityId];

    }

}

​

public class Child

{

// Actual properties don't matter 

}