Anagrams.cs

public static List<string> Anagrams()
{
    var star = string.Join("", "star".OrderBy(l => l));
    return "parts,traps,arts,rats,starts,tarts,rat,art,tar,tars,stars,stray"
        .Split(',')
        .Where(w => w.Length == star.Length && string.Join("", w.OrderBy(l => l)).Contains(star)).ToList();
}

ChristmasDayOfTheWeek.cs

public static List<string> ChristmasDayOfTheWeek()
{
    var start = new DateTime(2018, 12, 25);
    return Enumerable.Range(0, 8)
        .Select(y => start.AddYears(y))
        .Select(d => d.DayOfWeek.ToString()).ToList();
}

FullHouseHands.cs

public static List<string> FullHouseHands()
{
    var hands = "4♣ 5♦ 6♦ 7♠ 10♥;10♣ Q♥ 10♠ Q♠ 10♦;6♣ 6♥ 6♠ A♠ 6♦;2♣ 3♥ 3♠ 2♠ 2♦;2♣ 3♣ 4♣ 5♠ 6♠"
        .Split(';');
    var indexes = hands
        .Select((h, index) => (index: index,
            hand: h.Split(new[] {' ', '♣', '♦', '♠', '♥'}, StringSplitOptions.RemoveEmptyEntries)))
        .Select(t => (index: t.index, groups: t.hand.GroupBy(y => y)))
        .Where(t => t.groups.Count() == 2 && t.groups.First().Count() == 3)
        .Select(t => t.index);
    return indexes.Select(i => hands[i]).ToList();

}

LongestSequenceOfZeroes.cs

public static int LongestSequenceOfZeroes()
{
    return "1,2,1,1,0,3,1,0,0,2,4,1,0,0,0,0,2,1,0,3,1,0,0,0,6,1,3,0,0,0"
        .Split(',')
        .Aggregate((l: 0, m: 0),
            (t, s) => s == "0"
                ? (t.l + 1, Math.Max(t.l + 1, t.m))
                : (0, t.m)).m;
}

SharedInitials.cs

public static List<(string, List<string>)> SharedInitials()
{
    var players =
        "Santi Cazorla, Per Mertesacker, Alan Smith, Thierry Henry, Alex Song, Paul Merson, Alexis Sánchez, Robert Pires, Dennis Bergkamp, Sol Campbell"
            .Split(new[] {", "}, StringSplitOptions.RemoveEmptyEntries);
    return players
        .Select(p => (name: p, initials: string.Join("", p.Where(c => c >= 'A' && c <= 'Z').OrderBy(c => c))))
        .GroupBy(t => t.initials)
        .Select(t => (initials: t.Key, names: t.Select(x => x.name).ToList())).ToList();
}

VideoEditing.cs

public static string VideoEditing()
{
    var cuts = ("0:00:00-0:00:05;0:55:12-1:05:02;1:37:47-1:37:51" + "-2:00:00")
        .Split(new[] {'-', ';'}, StringSplitOptions.RemoveEmptyEntries);
    return string.Join(";", Enumerable.Range(0, cuts.Length / 2)
        .Select(i => $"{cuts[i * 2 + 1]}-{cuts[(i + 1) * 2]}"));
}