Question

Coupon collector is a classic statistic problem with many practical applications. The problem is to pick objects from a set of objects repeatedly and determine how many picks are needed for all the objects to be picked at least once. A variation of the problem is to pick cards from a shuffled deck of 52 cards repeatedly and find out how many picks are needed before you see one of each suit. Assume a picked card is placed back in the deck before picking another. Write a program to simulate the number of picks needed to get total of four cards from each different suit and display the four cards picked (it is possible that a card may be picked twice). Here is a sample run of the program:
4 of Diamonds
8 of Spades
Queen of Clubs
8 of Hearts
Number of picks: 9

Answer 1

Answer:

Here is the JAVA program:

public class Main {  //class name

public static void main(String[] args) {   //start of main method

//sets all boolean type variables spades, hearts diamonds and clubs to false initially

   boolean spades = false;  

   boolean hearts = false;

   boolean diamonds = false;

   boolean clubs = false;  

   String[] deck = new String[4];  //to store card sequence

   int index = 0;  //to store index position

   int NoOfPicks = 0;  //to store number of picks (picks count)

   while (!spades || !hearts || !diamonds || !clubs) {   //loop starts

       String card = printCard(getRandomCard());  //calls printCard method by passing getRandomCard method as argument to it to get the card

       NoOfPicks++;   //adds 1 to pick count

       if (card.contains("Spades") && !spades) {  //if that random card is a card of Spades and spades is not false

           deck[index++] = card;  //add that card to the index position of deck

           spades = true;  //sets spades to true

       } else if (card.contains("Hearts") && !hearts) {  //if that random card is a card of Hearts and hearts is not false

           deck[index++] = card;  

           hearts = true;   //sets hearts to true

       } else if (card.contains("Diamond") && !diamonds) {  //if that random card is a card of Diamond and diamonds is not false

           deck[index++] = card;

           diamonds = true;  //sets diamonds to true

       } else if (card.contains("Clubs") && !clubs) {  if that random card is a card of Clubs and clubs is not false

           deck[index++] = card;

           clubs = true;         }     }   //sets clubs to true

   for (int i = 0; i < deck.length; i++) {  //iterates through the deck i.e. card sequence array

       System.out.println(deck[i]);     }  //prints the card number in deck

   System.out.println("Number of picks: " + NoOfPicks);  }   //prints number of picks

public static int getRandomCard() {  //gets random card

   return (int) (Math.random() * 52); }   //generates random numbers of 52 range

public static String printCard(int cardNo) {   //displays rank number and suit

   String[] suits = { "Spades", "Hearts", "Diamonds", "Clubs", };  //array of suits

   String[] rankCards = { "Ace", "2", "3", "4", "5", "6", "7", "8", "9", "10",

           "Jack", "Queen", "King" };   //array of rank

  int suitNo = cardNo / 13;  //divides card number by 13 and stores to suitNo

 int rankNo = cardNo % 13;   //takes modulo of card number and 13 and store it to rankNo

   return rankCards[rankNo] + " of " + suits[suitNo];  }}  //returns rankCard at rankNo index and suits at suitNo index

Explanation:

The program is explained in the comments attached with each line of code. The screenshot of the program along with its output is attached.