12. Cards Frequencies

/* We are given a sequence of N playing cards from a standard deck.
 * The input consists of several cards (face + suit), separated by a space.
 * Write a program to calculate and print at the console the frequency
 * of each card face in format "card_face -> frequency".
 * The frequency is calculated by the formula appearances / N
 * and is expressed in percentages with exactly 2 digits after the decimal point.
 * The card faces with their frequency should be printed in the order of the card face's
 * first appearance in the input. The same card can appear multiple times in the input,
 * but it's face should be listed only once in the output. */

import java.util.ArrayList;
import java.util.HashMap;
import java.util.Scanner;

public class _12_CardsFrequencies {

    public static void main(String[] args) {
        // TODO Auto-generated method stub
        Scanner scan = new Scanner(System.in);
        System.out.println("Enter your Cards (face+suit) on single line, separated by a space:");
        String inputLine = scan.nextLine();

        String[] inputCards = inputLine.split("[^0-9AJQK]+");

        HashMap<String, Integer> cardsFrequency = new HashMap<>();
        for (String card : inputCards) {
            Integer count = cardsFrequency.get(card);
            if (count == null) {
                count = 0;
            }

            cardsFrequency.put(card, count + 1);
        }

        int allCards = inputCards.length;
        ArrayList<String> printedCards = new ArrayList<>();
        for (String key : inputCards) {
            if (printedCards.contains(key)) {
                continue;
            }
            int times = cardsFrequency.get(key);
            float frequency = ((float) times * 100) / allCards;
            System.out.printf("%s -> %.2f", key, frequency);
            System.out.println("%");
            printedCards.add(key);
        }
    }
}