Leetcode_1116_打印零和奇偶数_多线程-优快云博客

本文链接：https://blog.youkuaiyun.com/HDUCheater/article/details/115051200

本文介绍了一个使用信号量实现的多线程问题解决方案，通过三个信号量精确控制线程打印0、偶数和奇数，确保了按指定顺序输出。

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信号量

class ZeroEvenOdd {
    private int n;

    private final Semaphore sp0 = new Semaphore(1);
    private final Semaphore sp1 = new Semaphore(0);
    private final Semaphore sp2 = new Semaphore(0);

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

    // printNumber.accept(x) outputs "x", where x is an integer.
    public void zero(IntConsumer printNumber) throws InterruptedException {
        for (int i = 0; i < n; i++) {
            sp0.acquire();
            printNumber.accept(0);
            if(i%2==0){
                sp1.release();
            }else{
                sp2.release();
            }
        }
    }

    public void even(IntConsumer printNumber) throws InterruptedException {
        for (int i = 2; i <= n; i+=2) {
            sp2.acquire();
            printNumber.accept(i);
            sp0.release();
        }
    }

    public void odd(IntConsumer printNumber) throws InterruptedException {
        for (int i = 1; i <= n; i+=2) {
            sp1.acquire();
            printNumber.accept(i);
            sp0.release();
        }
    }
}

volatile

class ZeroEvenOdd {
    private int n;

    volatile private int Next = 0;

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

    // printNumber.accept(x) outputs "x", where x is an integer.
    public void zero(IntConsumer printNumber) throws InterruptedException {
        for (int i = 0; i < n; i++) {
            while(Next != 0) {
                Thread.yield();
            }
            printNumber.accept(0);
            if(i%2==0){
                Next = 1;
            }else{
                Next = 2;
            }
        }
    }

    public void even(IntConsumer printNumber) throws InterruptedException {
        for (int i = 2; i <= n; i+=2) {
            while(Next != 2) {
                Thread.yield();
            }
            printNumber.accept(i);
            Next = 0;
        }
    }

    public void odd(IntConsumer printNumber) throws InterruptedException {
        for (int i = 1; i <= n; i+=2) {
            while(Next != 1) {
                Thread.yield();
            }
            printNumber.accept(i);
            Next = 0;
        }
    }
}