LeetCode-多线程-1

1115. 交替打印 FooBar

信号量

class FooBar {
    private int n;
    private Semaphore fooSem, barSem;
    public FooBar(int n) {
        this.n = n;
        fooSem = new Semaphore(1);
        barSem = new Semaphore(0);
    }

    public void foo(Runnable printFoo) throws InterruptedException {

        for (int i = 0; i < n; i++) {

            // printFoo.run() outputs "foo". Do not change or remove this line.
            fooSem.acquire();
            printFoo.run();
            barSem.release();
        }
    }

    public void bar(Runnable printBar) throws InterruptedException {

        for (int i = 0; i < n; i++) {

            // printBar.run() outputs "bar". Do not change or remove this line.
            barSem.acquire();
            printBar.run();
            fooSem.release();
        }
    }
}

条件变量

class FooBar {
    private int n;
    Lock lock;
    Condition condition;
    boolean fooOrBar = true;
    public FooBar(int n) {
        this.n = n;
        lock = new ReentrantLock();
        condition = lock.newCondition();
    }

    public void foo(Runnable printFoo) throws InterruptedException {

        for (int i = 0; i < n; i++) {

            // printFoo.run() outputs "foo". Do not change or remove this line.
            lock.lock();
            while(!fooOrBar) {
                condition.await();
            }
            printFoo.run();
            fooOrBar = !fooOrBar;
            condition.signalAll();
            lock.unlock();
        }
    }

    public void bar(Runnable printBar) throws InterruptedException {

        for (int i = 0; i < n; i++) {

            // printBar.run() outputs "bar". Do not change or remove this line.
            lock.lock();
            while(fooOrBar) {
                condition.await();
            }
            printBar.run();
            fooOrBar = !fooOrBar;
            condition.signalAll();
            lock.unlock();
        }
    }
}

1116. 打印零与奇偶数