class Abc {
private int n;
// 标志位，控制执行顺序，0 执行 a，1 执行 b 2 执行 c
private volatile int type;
// 锁标志
private final Object object;

public Abc(int n) {
this.n = n;
object = new Object();
type = 0;
}

public void a(Runnable a) throws InterruptedException {
for (int i = 0; i < n; i++) {
synchronized (object) {
while (!(type == 0)) {
object.wait();
}
a.run();
type = 1;
object.notifyAll();
}
}
}

public void b(Runnable b) throws InterruptedException {
for (int i = 0; i < n; i++) {
synchronized (object) {
while (!(type == 1)) {
object.wait();
}
b.run();
type = 2;
object.notifyAll();
}
}
}

public void c(Runnable c) throws InterruptedException {
for (int i = 0; i < n; i++) {
synchronized (object) {
while (!(type == 2)) {
object.wait();
}
c.run();
type = 0;
object.notifyAll();
}
}
}

}