.NET Core Exercises

Exercise 1 (LINQ)

Construction using class initializers:

var buddies = new List<Buddy> {
    new Buddy(1, "Sylvester", "UK"),
    new Buddy(7, "Bogdan", "Poland", 51000.00m),
    // ...
};

Select distinct countries:

var countries = buddies
    .Select(buddy => buddy.Country)
    .Distinct();

List materialization:

var countries = buddies
    .Select(buddy => buddy.Country)
    .ToList();

Aggregate (reduce structure)

var buddiesByCountry = buddies
    .Aggregate<Buddy, Dictionary<string, int>>(
        new Dictionary<string, int>(),
        (dict, buddy) =>
        {
            if (dict.ContainsKey(buddy.Country))
                dict[buddy.Country] += 1;
            else
                dict[buddy.Country] = 1;
            return dict;
        }
    );

Any:

var buddiesFromUK = buddiesAll.All(buddy => buddy.Country == "UK");

Exercise 2 - LINQ

Intersect:

Product[] store1 = {
    new Product { Name = "apple", Code = 9 },
    new Product { Name = "orange", Code = 4 }, 
    new Product { Name = "lemon", Code = 29 }, 
    new Product { Name = "bannanas", Code = 7 } 
};
Product[] store2 = {
    new Product { Name = "apple", Code = 9 },
    new Product { Name = "lemon", Code = 12 }, 
    new Product { Name = "pinapple", Code = 15 },
    new Product { Name = "bannanas", Code = 7 },
};
var duplicates = store1.Intersect(store2);

Code Interview Exercise

Menu (restaurant):

var Menu = new Dictionary<string, List<string>> {
    { "starters", new List<string>(){ 
                "tartare", "pancake", "salad" } },
    { "mains", new List<string>(){ 
                "risotto", "lamb", "haddock", "salmon", "steak" } },
    { "desserts", new List<string>(){ 
                "sorbet", "icecream", "cheesecake" } }
};

List of dishes served by chef

var ChefMartinDishes = new List<string>() {
    "tartare", "risotto", "salmon", 
    "icecream", "pancake", "lamb"
};

Generate Menu items served by chef:

public string GenerateServed(string category)
{
    var list = Menu[category]
        .Intersect(ChefMartinDishes)
        .ToList();
    var sb = new StringBuilder();
    for (var i = 0; i < list.Count; i++) {
        if (i>0 && i == list.Count - 1)
            sb.Append(" or ");
        else if (i > 0)
            sb.Append(", ");
        sb.Append(list[i]);
    }
    return sb.ToString();
}