Styjun

I am having an issue shuffling two decks. I created two decks using a two dimensional array. Keep in mind that those were the requirements. I am also required to shuffle them using a method called shuffle() that takes in a 1D array and returns a 1D array.

After shuffling both decks I need to pick the first two card from the first deck and the first two cards from the second deck and check if they match. As well as the number of shuffles it took to get the result.

Sample output:

Two exact match cards from deck 1 are: Ace of Diamonds, 2 of Clubs

Two exact match cards from deck 2 are: Ace of Diamonds, 2 of Clubs

Number of shuffled times: 387

This is part two of a project we worked on and below is what I tried to solve this problem.

I tried creating decks using the code below which worked

int[][] deck = new int[2][52];

for (int i = 0; i <= deck.length - 1; i++) 
 for (int j = 0; j < deck[i].length; j++) 
 deck[i][j] = j;
 

And I wrote the shuffle method but it doesn't seem to work.

public static int[] shuffle(int[] deck) 
 for(int i=0; i<deck.length; i++) 
 int index = (int)(Math.random()* deck.length); 
 int temp = deck[i]; 
 deck[i] = deck[index];
 deck[index] = temp;
 
return deck; 

The code below is the original code from the first part of this project where we were required to print four of a kind from a single deck after shuffling it and counting how many shuffles it took to get four of a kind

class Main 
 public static void main(String[] args) 

 String[] suit = "Spades", "Hearts", "Diamond", "Clubs" ;

 String[] rank = "Ace", "1", "2", "3", "4", 
 "5", "6", "7", "8", "9",
 "10", "Jack", "Queen", "King" ;

 int rank1, rank2, rank3, rank4, suit1, suit2, suit3, suit4, count = 0; 

 int[] deck = new int[52];

 for (int i = 0; i < deck.length; i++) 
 deck[i] = i;
 

 do 

 count++;
 for (int i = 0; i < deck.length; i++) 

 int index = (int) (Math.random() * deck.length);
 int temp = deck[i];
 deck[i] = deck[index];
 deck[index] = temp;
 

 suit1 = deck[0] / 13;
 suit2 = deck[1] / 13;
 suit3 = deck[2] / 13;
 suit4 = deck[3] / 13;

 rank1 = deck[0] % 13;
 rank2 = deck[1] % 13;
 rank3 = deck[2] % 13;
 rank4 = deck[3] % 13;

 while (rank1 != rank2 

Once again result should look like this.

Sample output:

Two exact match cards from deck 1 are: Ace of Diamonds, 2 of Clubs
Two exact match cards from deck 2 are: Ace of Diamonds, 2 of Clubs

Number of shuffled times: 387

You shuffle method is correct. No need to do another shuffle method that will accept a 2D array. You will just have to call the shuffle method in each deck of your 2D array. To do this just :

deck[0] = shuffle(deck[0]);
deck[1] = shuffle(deck[1]);

I have also updated your code so that it can be easier to modify incase additional requirements arises. Refer to the code below:

public class Main 
 public static String[] card; // The holder for all cards

 public static void main(String[] args) 
 card = generateCardSuits(); // generate the cards with their corresponding suits
 doPartOne();
 doPartTwo();
 

 /**
 * Part One
 *
 */
 public static void doPartOne() 
 System.out.println("========== PART ONE ==========");
 int[] deck = generateAndShuffleInitialDeck();
 int ctr = 1;
 while (true) 
 if (deck[0] % 13 == deck[1] % 13 && deck[1] % 13 == deck[2] % 13 && deck[2] % 13 == deck[3] % 13) 
 break;
 
 deck = shuffle(deck);
 ctr++;
 
 System.out.println("Four-of-kind cards are: " + card[deck[0]] + " , " + card[deck[1]] + " , " + card[deck[2]]
 + " and " + card[deck[3]]);
 System.out.println("Number of shuffled times: " + ctr);
 System.out.println("==============================");
 

 /**
 * Part Two
 *
 */
 public static void doPartTwo() 
 System.out.println("========== PART TWO ==========");
 int[][] deck = new int[2][52];
 deck[0] = generateAndShuffleInitialDeck();
 deck[1] = generateAndShuffleInitialDeck();

 int ctr = 1;
 while (deck[0][0] != deck[1][0] 

 /**
 * Generate an initial deck of cards and shuffle them
 *
 * @return The initial and shuffled deck of cards
 */
 public static int[] generateAndShuffleInitialDeck() 
 int[] deck = new int[52];

 for (int j = 0; j < deck.length; j++) 
 deck[j] = j;
 
 return shuffle(deck);
 

 /**
 * Generate the cards with their corresponding suits
 *
 * @return The deck that will serve as the mapper for the cards to their suits
 */
 public static String[] generateCardSuits() 
 String[] rank = "Ace", "2", "3", "4", "5", "6", "7", "8", "9", "10", "Jack", "Queen", "King" ;
 String[] suit = "Spades", "Hearts", "Diamond", "Clubs" ;

 String[] cards = new String[52];

 for (int i = 0, j = 0, s = 0; i < cards.length; i++) 
 cards[i] = rank[j] + " of " + suit[s];
 j++;
 if (j == 13) // Since each suit consist of 13 cards
 j = 0;
 s++;
 
 
 return cards;
 

 /**
 * Shuffle the deck of cards
 *
 * @param deck
 * the deck of cards to be shuffle
 *
 * @return The shuffled deck of cards
 */
 public static int[] shuffle(int[] deck) 
 for (int i = 0; i < deck.length; i++) 
 int index = (int) (Math.random() * deck.length);
 int temp = deck[i];
 deck[i] = deck[index];
 deck[index] = temp;
 
 return deck;