链接：1115. 交替打印 FooBar - 力扣（LeetCode）
题解：
class FooBar { private: int n; std::mutex _mutex; std::condition_variable _cond1; // 用于 foo 等待 std::condition_variable _cond2; // 用于 bar 等待 int _status; // 1 表示打印 foo, 2 表示打印 bar public: FooBar(int n) : n(n), _status(1) {} void foo(std::function<void()> printFoo) { for (int i = 0; i < n; i++) { std::unique_lock<std::mutex> guard(_mutex); _cond1.wait(guard, [this] { return _status == 1; }); // printFoo() outputs "foo". Do not change or remove this line. printFoo(); _status = 2; _cond2.notify_one(); } } void bar(std::function<void()> printBar) { for (int i = 0; i < n; i++) { std::unique_lock<std::mutex> guard(_mutex); _cond2.wait(guard, [this] { return _status == 2; }); // printBar() outputs "bar". Do not change or remove this line. printBar(); _status = 1; _cond1.notify_one(); } } };