[GO] 两协程交替输出数字

package main

import (
    "fmt"
    "time"
)

func main() {

    for i := 1; i <= 10; i++ {
        go func(i int) {
            fmt.Println(2*i - 1)
        }(i)
    }

    for i := 1; i <= 10; i++ {
        go func(i int) {
            fmt.Println(2 * i)
        }(i)
    }

    time.Sleep(3 * time.Second)
}

package main

import (
    "fmt"
)

func main() {

    a := make(chan int)
    b := make(chan int)
    exit := make(chan int)

    go func() {
        for i := 1; i <= 20; i++ {
            fmt.Println(<-a)
            i++
            b <- i
        }
    }()

    go func() {
        for i := 0; i < 20; i++ {
            i++
            a <- i
            fmt.Println(<-b)
        }
        close(exit)
    }()

    <-exit
}