package q1115

type FooBar struct {
	n        int
	foo, bar chan struct{}
}

func NewFooBar(n int) *FooBar {
	ret := &FooBar{
		n:   n,
		foo: make(chan struct{}, 1),
		bar: make(chan struct{}, 1),
	}
	ret.bar <- struct{}{}
	return ret
}

func (fb *FooBar) Foo(printFoo func()) {
	for i := 0; i < fb.n; i++ {
		<-fb.bar
		// printFoo() outputs "foo". Do not change or remove this line.
		printFoo()

		fb.foo <- struct{}{}
	}
}

func (fb *FooBar) Bar(printBar func()) {
	for i := 0; i < fb.n; i++ {
		<-fb.foo
		// printBar() outputs "bar". Do not change or remove this line.
		printBar()

		fb.bar <- struct{}{}
	}
}