在c#中随机化泛型列表顺序的最佳方法是什么?我在一个列表中有一个有限的75个数字集,我想随机分配一个顺序,以便为彩票类型的应用程序绘制它们。


当前回答

通过使用元组进行交换,可以使Fisher-Yates shuffle更加简洁和富有表现力。

private static readonly Random random = new Random();

public static void Shuffle<T>(this IList<T> list)
{
    int n = list.Count;
    while (n > 1)
    {
        n--;
        int k = random.Next(n + 1);
        (list[k], list[n]) = (list[n], list[k]);
    }
}

其他回答

I'm bit surprised by all the clunky versions of this simple algorithm here. Fisher-Yates (or Knuth shuffle) is bit tricky but very compact. Why is it tricky? Because your need to pay attention to whether your random number generator r(a,b) returns value where b is inclusive or exclusive. I've also edited Wikipedia description so people don't blindly follow pseudocode there and create hard to detect bugs. For .Net, Random.Next(a,b) returns number exclusive of b so without further ado, here's how it can be implemented in C#/.Net:

public static void Shuffle<T>(this IList<T> list, Random rnd)
{
    for(var i=list.Count; i > 0; i--)
        list.Swap(0, rnd.Next(0, i));
}

public static void Swap<T>(this IList<T> list, int i, int j)
{
    var temp = list[i];
    list[i] = list[j];
    list[j] = temp;
}

试试这段代码。

    public static List<T> Randomize<T>(List<T> list)
    {
        List<T> randomizedList = new List<T>();
        Random rnd = new Random();
        while (list.Count > 0)
        {
            int index = rnd.Next(0, list.Count); //pick a random item from the master list
            randomizedList.Add(list[index]); //place it at the end of the randomized list
            list.RemoveAt(index);
        }
        return randomizedList;
    }

我在网上找到了一个有趣的解决办法。

礼貌:https://improveandrepeat.com/2018/08/a-simple-way-to-shuffle-your-lists-in-c/

var shuffled = myList。OrderBy(x => Guid.NewGuid()).ToList();

我通常使用:

var list = new List<T> ();
fillList (list);
var randomizedList = new List<T> ();
var rnd = new Random ();
while (list.Count != 0)
{
    var index = rnd.Next (0, list.Count);
    randomizedList.Add (list [index]);
    list.RemoveAt (index);
}
 public Deck(IEnumerable<Card> initialCards) 
    {
    cards = new List<Card>(initialCards);
    public void Shuffle() 
     }
    {
        List<Card> NewCards = new List<Card>();
        while (cards.Count > 0) 
        {
            int CardToMove = random.Next(cards.Count);
            NewCards.Add(cards[CardToMove]);
            cards.RemoveAt(CardToMove);
        }
        cards = NewCards;
    }

public IEnumerable<string> GetCardNames() 

{
    string[] CardNames = new string[cards.Count];
    for (int i = 0; i < cards.Count; i++)
    CardNames[i] = cards[i].Name;
    return CardNames;
}

Deck deck1;
Deck deck2;
Random random = new Random();

public Form1() 
{

InitializeComponent();
ResetDeck(1);
ResetDeck(2);
RedrawDeck(1);
 RedrawDeck(2);

}



 private void ResetDeck(int deckNumber) 
    {
    if (deckNumber == 1) 
{
      int numberOfCards = random.Next(1, 11);
      deck1 = new Deck(new Card[] { });
      for (int i = 0; i < numberOfCards; i++)
           deck1.Add(new Card((Suits)random.Next(4),(Values)random.Next(1, 14)));
       deck1.Sort();
}


   else
    deck2 = new Deck();
 }

private void reset1_Click(object sender, EventArgs e) {
ResetDeck(1);
RedrawDeck(1);

}

private void shuffle1_Click(object sender, EventArgs e) 
{
    deck1.Shuffle();
    RedrawDeck(1);

}

private void moveToDeck1_Click(object sender, EventArgs e) 
{

    if (listBox2.SelectedIndex >= 0)
    if (deck2.Count > 0) {
    deck1.Add(deck2.Deal(listBox2.SelectedIndex));

}

    RedrawDeck(1);
    RedrawDeck(2);

}