如何在java中使用in-shuffle和out-shuffle创建riffle shuffle

Question

我正在寻找创造一个即兴洗牌。我需要将我的牌组分成两个相等的部分(顶部和底部)，然后通过交错来自两个一半的单张卡片将这两个一半合并在一起。我已经创建了牌面，但我不知道如何将其一分为二。

这是我到目前为止所拥有的代码：

class Deck
{
    private static String[] suit = {"\u2660", "\u2666", "\u2663", "\u2764"};
    private static String[] rank = {"2", "3", "4", "5", "6", "7", "8", "9", "10", "Jack", "Queen", "King", "Ace"};
    private static String[] deck = new String[52];

    // create deck
    static
    {
        for (int i = 0; i < deck.length; i++)
        {
            deck[i] = rank[i % 13] + " of " + suit[i / 13];
        }
    }

    // un-shuffled deck
    static void deck()
    {
        for (int i = 0; i < deck.length; i++)
        {
            deck[i] = rank[i % 13] + " of " + suit[i / 13];
            System.out.println(deck[i]);
        }
    }
}

Answer 1

因为你的牌组由52张牌组成，你必须将它分成两组，每组26张牌。正如约阿希姆所说，你不需要为此创建一个新的数组，但可以考虑从deck25的甲板1和甲板2开始。下一步，你需要一张一张地检查每一副牌，并保存新的洗牌牌。

static String[] shuffleDeck(String[] unshuffledDeck) {
    // Buffer for deck we want to return
    String[] shuffledDeck = new String[unshuffledDeck.length];
    // We start at index 0 for our first deck (lower half)
    int firstDeckIndex = 0;
    // We start at half of the maximum length of the total deck for our second deck (upper half)
    int secondDeckIndex = unshuffledDeck.length / 2;
    // We start going through the indexes of the new deck which we are going to return
    for(int shuffledDeckIndex = 0; shuffledDeckIndex < shuffledDeck.length; shuffledDeckIndex++) {
        // This is for alternating between the two decks. The modulo operator (%) returns the remainder of a division
        // 0 % 2 == 0 equals to true, 1 % 2 == 0 equals to false, 2 % 2 == 0 equals to true etc. 
        if(shuffledDeckIndex % 2 == 0) {
            // We put the current card of the first deck inside our new shuffledDeck
            shuffledDeck[shuffledDeckIndex] = unshuffledDeck[firstDeckIndex];
            // We advance the index to get the next card of the first deck
            firstDeckIndex++;
        } else {
            // Same as with the first deck
            shuffledDeck[shuffledDeckIndex] = unshuffledDeck[secondDeckIndex];
            secondDeckIndex++;
        }
    }
    // We return the new shuffled deck
    return shuffledDeck;
}

我建议你一旦掌握了概念本身，就自己尝试实现一个新的函数。