package net.daporkchop;

import java.util.Arrays;
import java.util.Random;
import java.util.concurrent.ThreadLocalRandom;
import java.util.stream.IntStream;

public class Aufgabe7f {
    public static final int SAMPLES = 10_000;

    public static final int CARDS = 597;
    public static final int GROUP_SIZE = 3;

    public static final ThreadLocal<int[][]> TL_DECKS = ThreadLocal.withInitial(() -> new int[GROUP_SIZE][CARDS]);
    public static final ThreadLocal<int[]> TL_COUNTS = ThreadLocal.withInitial(() -> new int[GROUP_SIZE]);

    public static void main(String[] args) {
        double avgCount = IntStream.range(0, SAMPLES).parallel()
                .map(_i -> {
                    Random r = ThreadLocalRandom.current();
                    int[][] decks = TL_DECKS.get();
                    for (int[] deck : decks) {
                        Arrays.fill(deck, 0);
                    }
                    int[] counts = TL_COUNTS.get();
                    Arrays.fill(counts, 0);

                    int finishedDecks = 0;
                    int purchasedCount = 0;

                    while (finishedDecks < GROUP_SIZE) {
                        for (int player = 0; finishedDecks < GROUP_SIZE && player < GROUP_SIZE; player++) {
                            if (counts[player] == CARDS) {
                                continue;
                            }

                            int card = r.nextInt(CARDS);
                            if (decks[player][card]++ == 0) { //we've drawn the card for the first time
                                if (++counts[player] == CARDS) {
                                    finishedDecks++;
                                }
                            } else { //we already have the card, attempt to trade
                                TRADE:
                                for (int p = 0; p < GROUP_SIZE; p++) { //search for a player we can trade with
                                    if (p == player || counts[p] == CARDS || decks[p][card] != 0) {
                                        continue;
                                    }
                                    for (int c = 0; c < CARDS; c++) { //search for a card they can give us
                                        if (decks[player][c] == 0 //we don't have the card
                                                && decks[p][c] > 1) { //they have multiple instances of the card
                                            decks[player][c] = 1;
                                            decks[p][c]--;
                                            decks[p][card] = 1;
                                            if (++counts[player] == CARDS) {
                                                finishedDecks++;
                                            }
                                            if (++counts[p] == CARDS) {
                                                finishedDecks++;
                                            }
                                            break TRADE;
                                        }
                                    }
                                }
                            }
                            purchasedCount++;
                        }
                    }

                    return purchasedCount;
                })
                .average().orElseThrow();

        System.out.printf("purchased an average of %.2f cards (%.2f cards per person)\n", avgCount, avgCount / GROUP_SIZE);
    }
}