LeetCode（多线程）- 1116. 打印零与奇偶数

// 解决方案(1)
class ZeroEvenOdd {
    private int n;
    private volatile int state;
    public ZeroEvenOdd(int n) {
        this.n = n;
    }
    public void zero(IntConsumer printNumber) throws InterruptedException {
        for (int i = 0; i < n; i++) {
            while (state != 0) {
                Thread.yield();
            }
            printNumber.accept(0);
            if (i % 2 == 0) {
                state = 1;
            } else {
                state = 2;
            }
        }
    }
    public void even(IntConsumer printNumber) throws InterruptedException {
        for (int i = 2; i <= n; i += 2) {
            while (state != 2) {
                Thread.yield();
            }
            printNumber.accept(i);
            state = 0;
        }
    }
    public void odd(IntConsumer printNumber) throws InterruptedException {
        for (int i = 1; i <= n; i += 2) {
            while (state != 1) {
                Thread.yield();
            }
            printNumber.accept(i);
            state = 0;
        }
    }
}
// 解决方案(2)
class ZeroEvenOdd {
    private int n;
    private volatile int type = 0;
    private volatile boolean flag = true;
    private final Object obj = new Object();
    private volatile int num = 1;
    public ZeroEvenOdd(int n) {
        this.n = n;
    }
    // printNumber.accept(x) outputs "x", where x is an integer.
    public void zero(IntConsumer printNumber) throws InterruptedException {
        while (true) {
            synchronized (obj) {
                while (type != 0) {
                    obj.wait();
                }
                if (num > n) {
                    flag = false;
                    obj.notifyAll();
                    return;
                }
                printNumber.accept(0);
                if (num % 2 == 1) {
                    type = 1;
                } else {
                    type = 2;
                }
                obj.notifyAll();
            }
        }
    }
    public void even(IntConsumer printNumber) throws InterruptedException {
        while (true) {
            synchronized (obj) {
                while (flag && type != 2) {
                    obj.wait();
                }
                if (num > n) {
                    obj.notifyAll();
                    return;
                }
                printNumber.accept(num++);
                type = 0;
                obj.notifyAll();
            }
        }
    }
    public void odd(IntConsumer printNumber) throws InterruptedException {
        while (true) {
            synchronized (obj) {
                while (flag && type != 1) {
                    obj.wait();
                }
                if (num > n) {
                    obj.notifyAll();
                    return;
                }
                printNumber.accept(num++);
                type = 0;
                obj.notifyAll();
            }
        }
    }
}