static class QuickSort
{
    private static readonly Random _rnd = Random.Shared;

    public static List<T> Sort<T>(List<T> source, Comparer<T> comparer)
    {
        if (source.Count < 2)
            return source;

        var referenceIndex = _rnd.Next(source.Count);
        var reference = source[referenceIndex];
        var less = new List<T>();
        var equal = new List<T>();
        var more = new List<T>();

        for (var i = 0; i < source.Count; i++)
        {
            var value = source[i];
            if (comparer.Compare(value, reference) < 0)
                less.Add(value);
            else if (comparer.Compare(value, reference) > 0)
                more.Add(value);
            else if (comparer.Compare(value, reference) == 0)
                equal.Add(value);
        }
        less = Sort(less, comparer);
        more = Sort(more, comparer);
        var index = 0;
        foreach (var item in less)
            source[index++] = item;
        foreach (var item in equal)
            source[index++] = item;
        foreach (var item in more)
            source[index++] = item;
        return source;
    }
}