LeetCode（多线程）- 1195. 交替打印字符串

题目链接：点击打开链接

题目大意：略。

解题思路：略。

相关企业

• 字节跳动
• 微软（Microsoft）

AC 代码

// 方法1:CyclicBarrier
class FizzBuzz {

    private int n;

    private CyclicBarrier cb = new CyclicBarrier(4);

    public FizzBuzz(int n) {
        this.n = n;
    }

    // printFizz.run() outputs "fizz".
    public void fizz(Runnable printFizz) throws InterruptedException {
        for (int i = 1; i <= n; i++) {
            if (i % 3 == 0 && i % 5 != 0) {
                printFizz.run();
            }
            try {
                cb.await();
            } catch (BrokenBarrierException e) {
                e.printStackTrace();
            }
        }
    }

    // printBuzz.run() outputs "buzz".
    public void buzz(Runnable printBuzz) throws InterruptedException {
        for (int i = 1; i <= n; i++) {
            if (i % 3 != 0 && i % 5 == 0) {
                printBuzz.run();
            }
            try {
                cb.await();
            } catch (BrokenBarrierException e) {
                e.printStackTrace();
            }
        }
    }

    // printFizzBuzz.run() outputs "fizzbuzz".
    public void fizzbuzz(Runnable printFizzBuzz) throws InterruptedException {
        for (int i = 1; i <= n; i++) {
            if (i % 3 == 0 && i % 5 == 0) {
                printFizzBuzz.run();
            }
            try {
                cb.await();
            } catch (BrokenBarrierException e) {
                e.printStackTrace();
            }
        }
    }

    // printNumber.accept(x) outputs "x", where x is an integer.
    public void number(IntConsumer printNumber) throws InterruptedException {
        for (int i = 1; i <= n; i++) {
            if (i % 3 != 0 && i % 5 != 0) {
                printNumber.accept(i);
            }
            try {
                cb.await();
            } catch (BrokenBarrierException e) {
                e.printStackTrace();
            }
        }
    }
}

// 方法2:Semaphore
class FizzBuzz {
    private int n;

    private Semaphore number = new Semaphore(1);
    private Semaphore fizz = new Semaphore(0);
    private Semaphore buzz = new Semaphore(0);
    private Semaphore fizzbuzz = new Semaphore(0);


    public FizzBuzz(int n) {
        this.n = n;
    }

    // printFizz.run() outputs "fizz".
    public void fizz(Runnable printFizz) throws InterruptedException {
        for (int i = 1; i <= n; i++) {
            if (i % 3 == 0 && i % 5 != 0) {
                fizz.acquire();
                printFizz.run();
                number.release();
            }
        }
    }

    // printBuzz.run() outputs "buzz".
    public void buzz(Runnable printBuzz) throws InterruptedException {
        for (int i = 1; i <= n; i++) {
            if (i % 3 != 0 && i % 5 == 0) {
                buzz.acquire();
                printBuzz.run();
                number.release();
            }
        }
    }

    // printFizzBuzz.run() outputs "fizzbuzz".
    public void fizzbuzz(Runnable printFizzBuzz) throws InterruptedException {
        for (int i = 1; i <= n; i++) {
            if (i % 3 == 0 && i % 5 == 0) {
                fizzbuzz.acquire();
                printFizzBuzz.run();
                number.release();
            }
        }
    }

    // printNumber.accept(x) outputs "x", where x is an integer.
    public void number(IntConsumer printNumber) throws InterruptedException {
        for (int i = 1; i <= n; i++) {
            number.acquire();
            if (i % 3 != 0 && i % 5 != 0) {//开始打印
                printNumber.accept(i);
                number.release();
            } else if (i % 3 == 0 && i % 5 != 0) {//fizz开始打印
                fizz.release();
            } else if (i % 3 != 0 && i % 5 == 0) {//buzz开始打印
                buzz.release();
            } else {
                fizzbuzz.release();//fizzbuzz开始打印
            }
        }
    }
}

// 方法3:Semaphore
class FizzBuzz {
    private int n;

    private Semaphore semaphore = new Semaphore(1);
    private int cur = 1;

    public FizzBuzz(int n) {
        this.n = n;
    }

    // printFizz.run() outputs "fizz".
    public void fizz(Runnable printFizz) throws InterruptedException {
        while (true) {
            semaphore.acquire(1);
            try {
                // 原因就在这里，循环过程中如果打印的字符串个数已经满足要求，那么会使用return来返回，终止该方法的执行。
                // 但是咱们已经获取了信号量，那么在方法返回前需要释放该信号量，否则会导致其它线程一直等待，整个程序一直不结束。
                // Java语言中try-finally可以做到这一点，try-finally代码块也是常用的一种释放资源（IO流、数据库连接等）的方式。
                // 不是程序死循环，而是其它线程在wait，导致无法退出。
                if (cur > n) return;
                if (cur % 3 == 0 && cur % 5 != 0) {
                    cur++;
                    printFizz.run();
                }
            } finally {
                semaphore.release(1);
            }
        }
    }

    // printBuzz.run() outputs "buzz".
    public void buzz(Runnable printBuzz) throws InterruptedException {
        while (true) {
            semaphore.acquire(1);
            try {
                if (cur > n) return;
                if (cur % 3 != 0 && cur % 5 == 0) {
                    cur++;
                    printBuzz.run();
                }
            } finally {
                semaphore.release(1);
            }
        }
    }

    // printFizzBuzz.run() outputs "fizzbuzz".
    public void fizzbuzz(Runnable printFizzBuzz) throws InterruptedException {
        while (true) {
            semaphore.acquire(1);
            try {
                if (cur > n) return;
                if (cur % 3 == 0 && cur % 5 == 0) {
                    cur++;
                    printFizzBuzz.run();
                }
            } finally {
                semaphore.release(1);
            }
        }
    }

    // printNumber.accept(x) outputs "x", where x is an integer.
    public void number(IntConsumer printNumber) throws InterruptedException {
        while (true) {
            semaphore.acquire(1);
            try {
                if (cur > n) return;
                if (cur % 3 != 0 && cur % 5 != 0) {
                    printNumber.accept(cur);
                    cur++;
                }
            } finally {
                semaphore.release(1);
            }
        }
    }
}

// 方法4:Thread.yield()
class FizzBuzz {
    private int n;
    private volatile int state = 0; 
    public FizzBuzz(int n) {
        this.n = n;
    }

    public void fizz(Runnable printFizz) throws InterruptedException {
        for (int i = 3; i <= n; i += 3) {   //只输出3的倍数(不包含15的倍数)
            if (i % 15 == 0) continue;   //15的倍数不处理，交给fizzbuzz()方法处理
            while (state != 3)
                Thread.yield();

            printFizz.run();
            state = 0;
        }
    }

    public void buzz(Runnable printBuzz) throws InterruptedException {
        for (int i = 5; i <= n; i += 5) {   //只输出5的倍数(不包含15的倍数)
            if (i % 15 == 0)    //15的倍数不处理，交给fizzbuzz()方法处理
                continue;
            while (state != 5)
                Thread.yield();
            printBuzz.run();
            state = 0;
        }
    }

    public void fizzbuzz(Runnable printFizzBuzz) throws InterruptedException {
        for (int i = 15; i <= n; i += 15) {   //只输出15的倍数
            while (state != 15)
                Thread.yield();
            printFizzBuzz.run();
            state = 0;
        }
    }

    public void number(IntConsumer printNumber) throws InterruptedException {
        for (int i = 1; i <= n; ++i) {
            while (state != 0)
                Thread.yield();
            if (i % 3 != 0 && i % 5 != 0)
                printNumber.accept(i);
            else {
                if (i % 15 == 0)
                    state = 15;    //交给fizzbuzz()方法处理
                else if (i % 5 == 0)
                    state = 5;    //交给buzz()方法处理
                else
                    state = 3;    //交给fizz()方法处理
            }
        }
    }
}

// 方法5:ReentrantLock+Condition
class FizzBuzz {
    private int n;
    private ReentrantLock lock = new ReentrantLock();
    int state = 0;
    private Condition condition = lock.newCondition();

    public FizzBuzz(int n) {
        this.n = n;
    }

    // printFizz.run() outputs "fizz".
    public void fizz(Runnable printFizz) throws InterruptedException {
        for (int i = 3; i <= n; i += 3) {
            try {
                if (i % 3 == 0 && i % 5 == 0) continue;
                lock.lock();
                while (state != 3) {
                    condition.await();
                }
                printFizz.run();
                state = 0;
                condition.signalAll();
            } finally {
                lock.unlock();
            }
        }
    }

    // printBuzz.run() outputs "buzz".
    public void buzz(Runnable printBuzz) throws InterruptedException {
        for (int i = 5; i <= n; i += 5) {
            try {
                if (i % 3 == 0 && i % 5 == 0) continue;
                lock.lock();
                while (state != 5) {
                    condition.await();
                }
                printBuzz.run();
                state = 0;
                condition.signalAll();
            } finally {
                lock.unlock();
            }
        }
    }

    // printFizzBuzz.run() outputs "fizzbuzz".
    public void fizzbuzz(Runnable printFizzBuzz) throws InterruptedException {
        for (int i = 15; i <= n; i += 15) {
            try {
                lock.lock();
                while (state != 15) {
                    condition.await();
                }
                printFizzBuzz.run();
                state = 0;
                condition.signalAll();
            } finally {
                lock.unlock();
            }
        }
    }

    // printNumber.accept(x) outputs "x", where x is an integer.
    public void number(IntConsumer printNumber) throws InterruptedException {
        for (int i = 1; i <= n; i++) {
            try {
                lock.lock();
                while (state != 0) {
                    condition.await();
                }
                if (i % 3 != 0 && i % 5 != 0) {
                    printNumber.accept(i);
                } else {
                    if (i % 3 == 0 && i % 5 == 0) state = 15;
                    else if (i % 3 == 0) state = 3;
                    else if (i % 5 == 0) state = 5;
                    condition.signalAll();
                }
            } finally {
                lock.unlock();
            }
        }
    }
}

// 方法6:ReentrantLock+Condition
class FizzBuzz {

    private int n;

    private final ReentrantLock lock = new ReentrantLock();

    private final Condition condition = lock.newCondition();

    private int i = 1;

    public FizzBuzz(int n) {
        this.n = n;
    }

    // printFizz.run() outputs "fizz".
    public void fizz(Runnable printFizz) throws InterruptedException {
        while (true) {
            try {
                lock.lock();
                if (i > n) {
                    return;
                }
                while (i % 3 != 0) {
                    condition.signalAll();
                    condition.await();
                    if (i > n) {
                        return;
                    }
                }
                printFizz.run();
                i++;
            } finally {
                condition.signalAll();
                lock.unlock();
            }
        }
    }

    // printBuzz.run() outputs "buzz".
    public void buzz(Runnable printBuzz) throws InterruptedException {
        while (true) {
            try {
                lock.lock();
                if (i > n) {
                    return;
                }
                while (i % 5 != 0) {
                    condition.signalAll();
                    condition.await();
                    if (i > n) {
                        return;
                    }
                }
                printBuzz.run();
                i++;
            } finally {
                condition.signalAll();
                lock.unlock();
            }
        }
    }

    // printFizzBuzz.run() outputs "fizzbuzz".
    public void fizzbuzz(Runnable printFizzBuzz) throws InterruptedException {
        while (true) {
            try {
                lock.lock();
                if (i > n) {
                    return;
                }
                while (!(i % 3 == 0 && i % 5 == 0)) {
                    condition.signalAll();
                    condition.await();
                    if (i > n) {
                        return;
                    }
                }
                printFizzBuzz.run();
                i++;
            } finally {
                condition.signalAll();
                lock.unlock();
            }
        }
    }

    // printNumber.accept(x) outputs "x", where x is an integer.
    public void number(IntConsumer printNumber) throws InterruptedException {
        while (true) {
            try {
                lock.lock();
                if (i > n) {
                    return;
                }
                while (i % 3 == 0 || i % 5 == 0) {
                    condition.signalAll();
                    condition.await();
                    if (i > n) {
                        return;
                    }
                }
                printNumber.accept(i);
                i++;
            } finally {
                condition.signalAll();
                lock.unlock();
            }
        }
    }
}