The problem
Coupon collector is a classic statistics problem with many practical applications. The problem is to pick objects from a set of objects repeatedly 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).
Breaking it down
public static void main(String[] args) {
boolean spades = false;
boolean hearts = false;
boolean diamond = false;
boolean clubs = false;
String[] cardSequence = new String[4];
int index = 0;
int pickCount = 0;
while (!spades || !hearts || !diamond || !clubs) {
String card = revealCard(getCard());
pickCount++;
if (card.contains("Spades") && !spades) {
cardSequence[index++] = card;
spades = true;
} else if (card.contains("Hearts") && !hearts) {
cardSequence[index++] = card;
hearts = true;
} else if (card.contains("Diamond") && !diamond) {
cardSequence[index++] = card;
diamond = true;
} else if (card.contains("Clubs") && !clubs) {
cardSequence[index++] = card;
clubs = true;
}
}
for (int i = 0; i < cardSequence.length; i++) {
System.out.println(cardSequence[i]);
}
System.out.println("Pick count = " + pickCount);
}
public static int getCard() {
return (int) (Math.random() * 52);
}
public static String revealCard(int cardNum) {
String[] suit = { "Spades", "Hearts", "Diamonds", "Clubs", };
String[] ranks = { "Ace", "2", "3", "4", "5", "6", "7", "8", "9", "10",
"Jack", "Queen", "King" };
int suitNum = cardNum / 13;
int rankNum = cardNum % 13;
return ranks[rankNum] + " of " + suit[suitNum];
}Output
4 of Clubs
9 of Hearts
3 of Spades
7 of Diamonds
Pick count = 8