LeetCode 1195. Fizz Buzz Multithreaded

原题链接在这里：https://leetcode.com/problems/fizz-buzz-multithreaded/

题目：

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

题解：

User synchronized method.

For the current number, when it fulfills the condition, print. Otherwise, wait.

Time Complexity: O(1).

Space: O(1).

AC Java:

class FizzBuzz {
    private int n;
    private int cur;

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

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

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

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

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

类似Fizz Buzz.