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:

 1 class FizzBuzz {
 2     private int n;
 3     private int cur;
 4 
 5     public FizzBuzz(int n) {
 6         this.n = n;
 7         this.cur = 1;
 8     }
 9 
10     // printFizz.run() outputs "fizz".
11     public synchronized void fizz(Runnable printFizz) throws InterruptedException {
12         while(cur <= n){
13             if(cur % 3 == 0 && cur % 5 != 0){
14                 printFizz.run();
15                 cur++;
16                 notifyAll();
17             }else{
18                 wait();
19             }
20         }
21     }
22 
23     // printBuzz.run() outputs "buzz".
24     public synchronized void buzz(Runnable printBuzz) throws InterruptedException {
25         while(cur <= n){
26             if(cur % 3 != 0 && cur % 5 == 0){
27                 printBuzz.run();
28                 cur++;
29                 notifyAll();
30             }else{
31                 wait();
32             }
33         }
34     }
35 
36     // printFizzBuzz.run() outputs "fizzbuzz".
37     public synchronized void fizzbuzz(Runnable printFizzBuzz) throws InterruptedException {
38         while(cur <= n){
39             if(cur % 3 == 0 && cur % 5 == 0){
40                 printFizzBuzz.run();
41                 cur++;
42                 notifyAll();
43             }else{
44                 wait();
45             }
46         }
47     }
48 
49     // printNumber.accept(x) outputs "x", where x is an integer.
50     public synchronized void number(IntConsumer printNumber) throws InterruptedException {
51         while(cur <= n){
52             if(cur % 3 != 0 && cur % 5 != 0){
53                 printNumber.accept(cur);
54                 cur++;
55                 notifyAll();
56             }else{
57                 wait();
58             }
59         }
60     }
61 }

类似Fizz Buzz.