LeetCode - Fizz Buzz Multithreaded

Posted 2021-03-15 IncredibleThings

Write a program that outputs the string representation of numbers from 1 to n, however:

If the number is divisible by 3, output "fizz".
If the number is divisible by 5, output "buzz".
If the number is divisible by both 3 and 5, output "fizzbuzz".
For example, for n = 15, we output: 1, 2, fizz, 4, buzz, fizz, 7, 8, fizz, buzz, 11, fizz, 13, 14, fizzbuzz.

Suppose you are given the following code:

class FizzBuzz {
  public FizzBuzz(int n) { ... }               // constructor
  public void fizz(printFizz) { ... }          // only output "fizz"
  public void buzz(printBuzz) { ... }          // only output "buzz"
  public void fizzbuzz(printFizzBuzz) { ... }  // only output "fizzbuzz"
  public void number(printNumber) { ... }      // only output the numbers
}
Implement a multithreaded version of FizzBuzz with four threads. The same instance of FizzBuzz will be passed to four different threads:

Thread A will call fizz() to check for divisibility of 3 and outputs fizz.
Thread B will call buzz() to check for divisibility of 5 and outputs buzz.
Thread C will call fizzbuzz() to check for divisibility of 3 and 5 and outputs fizzbuzz.
Thread D will call number() which should only output the numbers.

 

class FizzBuzz {
    private int n;
    private volatile int count = 1;

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

    // printFizz.run() outputs "fizz".
    public void fizz(Runnable printFizz) throws InterruptedException {
        synchronized(this){
            while (count <= n) {
                if(count % 3 == 0 && count % 5 != 0) {
                    printFizz.run();
                    count++;
                    this.notifyAll();
                }
                else {
                    this.wait();
                }
            }
        }
    }

    // printBuzz.run() outputs "buzz".
    public void buzz(Runnable printBuzz) throws InterruptedException {
        synchronized(this){
            while (count <= n) {
                if(count % 5 == 0 && count % 3 != 0) {
                    printBuzz.run();
                    count++;
                    this.notifyAll();
                }
                else {
                    this.wait();
                }
            }   
        }
    }

    // printFizzBuzz.run() outputs "fizzbuzz".
    public void fizzbuzz(Runnable printFizzBuzz) throws InterruptedException {
        synchronized(this){
            while (count <= n) {
                if(count % 5 == 0 && count % 3 == 0) {
                    printFizzBuzz.run();
                    count++;
                    this.notifyAll();
                }
                else {
                    this.wait();
                }
            }                 
        }        
    }

    // printNumber outputs "x", where x is an integer.
    public void number(IntConsumer printNumber) throws InterruptedException {
        synchronized(this){
            while (count <= n) {
                if(count % 5 != 0 && count % 3 != 0) {
                    printNumber.accept(count);
                    count++;
                    this.notifyAll();
                }
                else {
                    this.wait();
                }
            }  
        }        
    }
}