Go语言面试题：交替打印数字和字母

goroutinegoroutinegoroutine

12AB34CD56EF78GH910IJ1112KL1314MN1516OP1718QR1920ST2122UV2324WX2526YZ2728

channelgoroutine

numberchannelgoroutine

letterchannelgoroutine

number, letter := make(chan bool), make(chan bool)

goroutinenumberletter

go func() {
str := "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
i := 0
	for {
        <- letter
        if i >= utf8.RuneCountInString(str) {
                return
		}
	    fmt.Print(str[i : i+2])
	    i += 2
	    number <- true
	}
}()

syn.WaitGroup

package main

import (
        "fmt"
        "sync"
        "unicode/utf8"
)

func main() {
        number, letter := make(chan bool), make(chan bool)
        wait := sync.WaitGroup{}
        go func() {
                i := 1
                for {
           			<- number
                    fmt.Printf("%d%d", i, i + 1)
                    i += 2
                    letter <- true
                }
        }()
        wait.Add(1)
        go func(wait *sync.WaitGroup) {
                str := "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
                i := 0
                for {
                    <- letter
                    if i >= utf8.RuneCountInString(str) {
                            wait.Done()
                            return
                    }
                    fmt.Print(str[i : i+2])
                    i += 2
                    number <- true
                }
        }(&wait)
        number <- true
        wait.Wait()
}