Question: Coupon collector is a classic statistics problem with many practical applications. The problem is to repeatedly pick objects from a set of objects and find out 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 four cards from each suit and display the four cards picked (it is possible a card may be picked twice).

Sample input/output

```
Two of Spades
Six of Hearts
Queen of Clubs
Four of Diamonds
Number of picks: 2
```

package Ch7; /* Q: Coupon collector is a classic statistics problem with many practical applications. The problem is to repeatedly pick objects from a set of objects and find out 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 four cards from each suit and display the four cards picked (it is possible a card may be picked twice). */ /* Task: pick cards from a shuffled deck of 52 cards repeatedly 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 Step 1: Create an array of suite names, an array of card name, an array of card number (0-51) Step 2: Initialize cardNumber array with values from 1-52 Step 3: Shuffle the deck Step 4: pick 4 cards Step 5: Check if they are all different suites Step 6: if no- Pick again and increase count Step 7: if yes- display the cards and number of picks */ import org.jetbrains.annotations.NotNull; public class Ex23_2 { final static int DECK_SIZE=52; final static int PICK_SIZE=4; public static void main(String[] args) { //Step 1: Create an array of suite names, an array of card name, an array of card number (0-51) String[] suitNames= {"Hearts", "Diamonds", "Spades", "Clubs"}; String[] cardNames= {"Ace", "Two", "Three", "Four", "Five", "Six", "Seven", "Eight", "Nine", "Ten", "Jack", "Queen", "King"}; int[] cardNumber= new int[DECK_SIZE]; int[] pickedCards= new int[PICK_SIZE]; //Step 2: Initialize cardNumber array with values from 1-52 initializeDeck(cardNumber); // Step 3: Shuffle the deck shuffleCards(cardNumber); boolean isDiffSuite; int count=0; do{ //Step 4: pick 4 cards pickCards(cardNumber, pickedCards); isDiffSuite= isDifferentSuite(pickedCards); count++; }while(!isDiffSuite); // Step 5 and 6: Check if they are all different suites; if no- Pick again and increase count //Step 7: if yes- display the cards and number of picks displayResults(suitNames, cardNames, pickedCards, count); } public static void initializeDeck(int[] cardNumber){ for(int i=0; i<cardNumber.length; i++){ cardNumber[i]=(i+1); } } public static void shuffleCards(int[] cardNumber){ for(int i=0; i<cardNumber.length; i++){ int randomIndex= (int)(Math.random()*DECK_SIZE); int temp= cardNumber[i]; cardNumber[i]= cardNumber[randomIndex]; cardNumber[randomIndex]=temp; } } public static void pickCards(int[] cardNumber, int[] pickedCards){ for(int i=0; i<pickedCards.length; i++){ int randomIndex= (int)(Math.random()*DECK_SIZE); pickedCards[i]= cardNumber[randomIndex]; } } public static boolean isDifferentSuite(int[] pickedCards){ for(int i=0; i<pickedCards.length; i++){ for(int j=0; j<pickedCards.length; j++){ if(i!=j && ((pickedCards[j]/13)==(pickedCards[i]/13))){ return false; } } } return true; } public static void displayResults(String[] suitNames, String[] cardNames, int[] pickedCards, int count){ for(int i=0; i<pickedCards.length; i++){ System.out.println(cardNames[(pickedCards[i]-1)%13] + " of " + suitNames[(pickedCards[i]-1)/13]); } System.out.println("Number of picks: " + count); } } /* Sample input/output Two of Spades Six of Hearts Queen of Clubs Four of Diamonds Number of picks: 2 */