考拉兹猜想 Collatz conjecture

Collatz conjecture .txt

public class CollatzConjecture {
    AtomicInteger max = new AtomicInteger(0);
    int[] ints = new int[100000001];

    public static void main(String[] args) {
        CollatzConjecture test = new CollatzConjecture();
        long timestamp = System.currentTimeMillis();
        System.out.println(test.count());
        System.out.println(System.currentTimeMillis() - timestamp);
    }

    int count() {
        CountDownLatch countLatchTest = new CountDownLatch(10);

        for (int i = 0; i < 10; i++) {
            int finalI = i;
            new Thread(() -> {
                for (int j = 0; j < 10000000; j++) {
                    if (j % 1000000 == 0)
                        System.out.println(j);
                    int num = j * 10 + finalI;
                    max.compareAndSet(max.get(), Math.max(collatz(num), max.get()));
                }
                countLatchTest.countDown();
            }).start();
        }
        try {
            countLatchTest.await();
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
        return max.get();
    }


    int collatz(long n) {
        int index = 1;
        final long x = n;
        while (n > 1) {
            if (n < 100000000 && ints[(int) n] != 0) {
                index += ints[(int) n] - 1;
                break;
            }
            if (n % 2 == 0) {
                n = n / 2;
            } else {
                n = n * 3 + 1;
            }
            index++;
        }
        if (ints[(int) x] == 0)
            ints[(int) x] = index;
        return index;
    }
}