// https://leetcode.com/problems/building-h2o/

//

// algorithms

// Hard (38.48%)

// Total Accepted: 197

// Total Submissions: 512

// beats 100.0% of java submissions

import java.util.concurrent.Semaphore;

class H2O {

private Semaphore hSemaphore = new Semaphore(0);

private Semaphore oSemaphore = new Semaphore(1);

private int count;

public H2O() {}

public void hydrogen(Runnable releaseHydrogen) throws InterruptedException {

hSemaphore.acquire();

// releaseHydrogen.run() outputs "H". Do not change or remove this line.

releaseHydrogen.run();

count++;

if ((count & 1) == 0) {

oSemaphore.release();

}

}

public void oxygen(Runnable releaseOxygen) throws InterruptedException {

oSemaphore.acquire();

releaseOxygen.run();

hSemaphore.release();

hSemaphore.release();

}

}