package seelman;

public class Seelman {

	// 500 million (max_int is only 2.1b)
	public static final int SEQUENCE_MAX = 500000000;

	public static final int SEQUENCE_LENGTH = SEQUENCE_MAX;

	// sequence[i] is the sequence, i.e. sequence[1] = 1, sequence[2] = 3
	int[] sequence = new int[SEQUENCE_LENGTH];

	// is the value (already) in the sequence?
	boolean[] sequenced = new boolean[SEQUENCE_MAX];

	public void checkForEmpties() {
		/*
		 * If any sequence from n to (2n-1) is all sequenced while any value x <
		 * n is not sequenced, then that value x will be unreachable.
		 */

		int firstUnsequenced = SEQUENCE_MAX;
		for (int i = 1; i < SEQUENCE_MAX; i++) {
			if (!sequenced[i]) {
				firstUnsequenced = i;
				break;
			}
		}

		for (int start = firstUnsequenced + 1; start <= SEQUENCE_MAX / 2; start++) {
			boolean broken = false;
			for (int i = start; i < start * 2; i++) {
				if (!sequenced[i]) {
					broken = true;
					break;
				}
			}
			if (!broken) {
				System.out.println("The value " + firstUnsequenced + " is not in the sequence, but every value from "
						+ start + " to " + (start * 2 - 1) + " is.");
				return;
			}
		}

	}

	public void createSequence() {
		String str = "";

		for (int i = 1; i < SEQUENCE_LENGTH; i++) {
			int value;
			if (i == 1) {
				value = 1;
			} else {
				int prev = sequence[i - 1];
				value = prev / 2 + prev % 2;
				if (sequenced[value]) {
					value = prev * 3;
				}
			}

			if (value > SEQUENCE_MAX) {
				System.out.println(str);
				System.out.println("Exceeded sequence max after " + i + " entries.");
				checkForEmpties();
				return;
			}

			if (sequenced[value]) {
				System.out.println(str);
				System.out.println("Sequence repeat.");
				return;
			}

			sequence[i] = value;
			sequenced[value] = true;

			str += value + " ";
			if (str.length() > 64) {
				System.out.println(str);
				str = "";
			}
		}
	}

	public static void main(String[] args) {
		Seelman s = new Seelman();

		s.createSequence();
	}
}