package main

import (
    "sync"
)

var count = 5
func main(){

    wg:=sync.WaitGroup{}
    chanA :=make(chan struct{},1)
    chanB :=make(chan struct{},1)
    chanC :=make(chan struct{},1)


    chanA<- struct{}{}
    wg.Add(3)

    go printA(&wg,chanA,chanB)
    go printB(&wg,chanB,chanC)
    go printC(&wg,chanC,chanA)
    wg.Wait()
}

func printA(wg *sync.WaitGroup, chanA chan struct{}, chanB chan struct{}) {
    defer wg.Done()

    for i:=0;i<count;i++{
        <-chanA
        println("A")
        chanB<- struct{}{}
    }
}

func printB(wg *sync.WaitGroup, chanB chan struct{}, chanC chan struct{}) {
    defer wg.Done()

    for i:=0;i<count;i++{
        <-chanB
        println("B")
        chanC<- struct{}{}
    }
}

func printC(wg *sync.WaitGroup, chanC chan struct{}, chanA chan struct{}) {
    defer wg.Done()

    for i:=0;i<count;i++{
        <-chanC
        println("C")
        chanA<- struct{}{}
    }
}

image.png