2个协程交替打印字母和数字

答案1：

package main
import (
    "fmt"
)
func main() {
    limit := 26
    numChan := make(chan int, 1)
    charChan := make(chan int, 1)
    mainChan := make(chan int, 1)
    charChan <- 1
    go func() {
        for i := 0; i < limit; i++ {
            <-charChan
            fmt.Printf("%c\n", 'a'+i)
            numChan <- 1
        }
    }()
    go func() {
        for i := 0; i < limit; i++ {
            <-numChan
            fmt.Println(i)
            charChan <- 1
        }
        mainChan <- 1
    }()
    <-mainChan
    close(charChan)
    close(numChan)
    close(mainChan)
}