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path: root/go/nth-prime/nth_prime.go
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package prime

func gen() (chan int, chan bool) {
	stop := make(chan bool)
	ch := make(chan int)
	go func() {
		defer close(ch)
		for i := 2; ; i++ {
			select {
			case ch <- i:
			case <-stop:
				return
			}
		}
	}()
	return ch, stop
}

func filter(in chan int, prime int) chan int {
	ch := make(chan int)
	go func() {
		defer close(ch)
		for i := range in {
			if i%prime != 0 {
				ch <- i
			}
		}
	}()
	return ch
}

func Nth(n int) (int, bool) {
	if n < 1 {
		return 0, false
	}
	ch, stop := gen()
	defer func() { stop <- true }()
	for i := 1; i < n; i++ {
		ch = filter(ch, <-ch)
	}
	return <-ch, true
}