import java.util.ArrayList;
import java.util.Random;

public class BulgarianSolitaire {

	public static void main(String[] args) {

		// You do not need to handle the User Interface (UI).
		// Instead you can run the JUnit test cases found in
		// ArrayListExercisesTests.java
		bulgarianSolitaire(10);
	}

public static void bulgarianSolitaire(int numCards) {

	    // Check if the given number of cards is triangular

int n = (int) Math.sqrt(2 * numCards);
	    if (n * (n + 1) / 2 != numCards) {
	        System.out.println(numCards + " is not triangular");
	        return;
	    }

	    ArrayList<Integer> finalArray = new ArrayList();
	    int sum = 0;
	    for (int i = 1; sum + i <= numCards; i++) {
	        finalArray.add(i);
	        sum += i;
	    }

	    ArrayList<Integer> pileOfCards = new ArrayList();
	    Random random = new Random();
	    int remaining = numCards;

	    while (remaining > 0) {
	        int pile = random.nextInt(remaining) + 1;
	        pileOfCards.add(pile);
	        remaining -= pile;
	    }

	    System.out.println(pileOfCards);

	    while (!pileOfCards.equals(finalArray)) {
	        int leftovers = 0;

	        for (int i = 0; i < pileOfCards.size(); i++) {
	            pileOfCards.set(i, pileOfCards.get(i) - 1);
	            leftovers++;
	        }

	        pileOfCards.removeIf(pile -> pile == 0);
	        pileOfCards.add(leftovers);
	        System.out.println(pileOfCards);
	    }
	}
}