1195. Fizz Buzz Multithreaded.cpp

// ***
//
// 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
//
// ***

class FizzBuzz {
private:
    int n;

    mutex m;
    condition_variable cvJustFinished;
    int lastNum = 0;

public:
    FizzBuzz(int n) { this->n = n; }

    // printFizz() outputs "fizz".
    void fizz(function<void()> printFizz) {
        for (int i = 1; i <= n; i++) {
            if (i % 3 == 0 and i % 5 != 0) {
                unique_lock<mutex> lk(m);
                cvJustFinished.wait(lk, [this, i] { return lastNum == i - 1; });

                printFizz();

                lastNum = i;
                cvJustFinished.notify_all();
            }
        }
    }

    // printBuzz() outputs "buzz".
    void buzz(function<void()> printBuzz) {
        for (int i = 1; i <= n; i++) {
            if (i % 3 != 0 and i % 5 == 0) {
                unique_lock<mutex> lk(m);
                cvJustFinished.wait(lk, [this, i] { return lastNum == i - 1; });

                printBuzz();

                lastNum = i;
                cvJustFinished.notify_all();
            }
        }
    }

    // printFizzBuzz() outputs "fizzbuzz".
    void fizzbuzz(function<void()> printFizzBuzz) {
        for (int i = 1; i <= n; i++) {
            if (i % 3 == 0 and i % 5 == 0) {
                unique_lock<mutex> lk(m);
                cvJustFinished.wait(lk, [this, i] { return lastNum == i - 1; });

                printFizzBuzz();

                lastNum = i;
                cvJustFinished.notify_all();
            }
        }
    }

    // printNumber(x) outputs "x", where x is an integer.
    void number(function<void(int)> printNumber) {
        for (int i = 1; i <= n; i++) {
            if (i % 3 != 0 and i % 5 != 0) {
                unique_lock<mutex> lk(m);
                cvJustFinished.wait(lk, [this, i] { return lastNum == i - 1; });

                printNumber(i);

                lastNum = i;
                cvJustFinished.notify_all();
            }
        }
    }
};