using System;
using System.Collections.Generic;
using System.Linq; 
using System.Text;

namespace First_week
{
    internal static class CollectionUtils
    {
        public static bool IsNullOrEmpty<T>(this IEnumerable<T> collection)
        {
            return collection == null || !collection.Any();
        }
        public static List<T> ToSafeList<T>(this IEnumerable<T> collection)
        {
            return collection?.ToList() ?? new List<T>();
        }

        public static void Shuffle<T>(this IList<T> list)
        {
            if (list == null)
                return;

            Random rng = new Random();
            int n = list.Count;
            while (n > 1)
            {
                n--;
                int k = rng.Next(n + 1);
                T value = list[k];
                list[k] = list[n];
                list[n] = value;
            }
        }
    }
}