List 的随机副本[duplicate]

public static void Shuffle<T>(this IList<T> list)  
{  
    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;  
    }  
}

public List<T> Random<T>(this IEnumerable<T> collection)
{
    return collection.OrderBy(i => Guid.NewGuid()).ToList();
}