LeetCode-in-Java

1195. Fizz Buzz Multithreaded

Medium

You have the four functions:

• printFizz that prints the word "Fizz" to the console,
• printBuzz that prints the word "Buzz" to the console,
• printFizzBuzz that prints the word "FizzBuzz" to the console, and
• printNumber that prints a given integer to the console.

You are given an instance of the class FizzBuzz that has four functions: fizz, buzz, fizzbuzz and number. The same instance of FizzBuzz will be passed to four different threads:

• Thread A: calls fizz() that should output the word "Fizz".
• Thread B: calls buzz() that should output the word "Buzz".
• Thread C: calls fizzbuzz() that should output the word "FizzBuzz".
• Thread D: calls number() that should only output the integers.

Modify the given class to output the series [1, 2, "Fizz", 4, "Buzz", ...] where the ith token (1-indexed) of the series is:

• "FizzBuzz" if i is divisible by 3 and 5,
• "Fizz" if i is divisible by 3 and not 5,
• "Buzz" if i is divisible by 5 and not 3, or
• i if i is not divisible by 3 or 5.

Implement the FizzBuzz class:

• FizzBuzz(int n) Initializes the object with the number n that represents the length of the sequence that should be printed.
• void fizz(printFizz) Calls printFizz to output "Fizz".
• void buzz(printBuzz) Calls printBuzz to output "Buzz".
• void fizzbuzz(printFizzBuzz) Calls printFizzBuzz to output "FizzBuzz".
• void number(printNumber) Calls printnumber to output the numbers.

Example 1:

Input: n = 15

Output: [1,2,”fizz”,4,”buzz”,”fizz”,7,8,”fizz”,”buzz”,11,”fizz”,13,14,”fizzbuzz”]

Example 2:

Input: n = 5

Output: [1,2,”fizz”,4,”buzz”]

Constraints:

• 1 <= n <= 50

Solution

import java.util.function.IntConsumer;

@SuppressWarnings("java:S1130")
public class FizzBuzz {
    private final int n;
    private int current;

    public FizzBuzz(int n) {
        this.n = n;
        this.current = 1;
    }

    // printFizz.run() outputs "fizz".
    public void fizz(Runnable printFizz) throws InterruptedException {
        synchronized (this) {
            while (current <= n) {
                if (current % 3 == 0 && current % 5 != 0) {
                    printFizz.run();
                    current += 1;
                    notifyAll();
                } else {
                    wait();
                }
            }
        }
    }

    // printBuzz.run() outputs "buzz".
    public void buzz(Runnable printBuzz) throws InterruptedException {
        synchronized (this) {
            while (current <= n) {
                if (current % 3 != 0 && current % 5 == 0) {
                    printBuzz.run();
                    current += 1;
                    notifyAll();
                } else {
                    wait();
                }
            }
        }
    }

    // printFizzBuzz.run() outputs "fizzbuzz".
    public void fizzbuzz(Runnable printFizzBuzz) throws InterruptedException {
        synchronized (this) {
            while (current <= n) {
                if (current % 15 == 0) {
                    printFizzBuzz.run();
                    current += 1;
                    notifyAll();
                } else {
                    wait();
                }
            }
        }
    }

    // printNumber.accept(x) outputs "x", where x is an integer.
    public void number(IntConsumer printNumber) throws InterruptedException {
        synchronized (this) {
            while (current <= n) {
                if (current % 3 != 0 && current % 5 != 0) {
                    printNumber.accept(current);
                    current += 1;
                    notifyAll();
                } else {
                    wait();
                }
            }
        }
    }
}

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