交替打印数字字母的另外一种实现方法 about interview-go HOT 7 OPEN

package main

import (
	"runtime"
	"sync"
	"fmt"
)

const N = 10

func main() {
	runtime.GOMAXPROCS(1)
	wg := &sync.WaitGroup{}
	wg.Add(N*2)
	for i := 0; i < N; i++ {
		m := i
		go func(m int) {
			defer wg.Done()
			fmt.Print(m)
		}(m)
		go func(m int) {
			defer wg.Done()
			runtime.Gosched()
			fmt.Printf(`%c`,'A'+m)
		}(m)
	}
	wg.Wait()
}

package main
import (
  "fmt"
)

// POINT: communicate between goroutines by channel

//使用两个 goroutine 交替打印序列，一个 goroutine 打印数字， 另外一个 goroutine 打印字母， 最终效果如下：
//12AB34CD56EF78GH910IJ1112KL1314MN1516OP1718QR1920ST2122UV2324WX2526YZ2728
func AlterPrint(){
  letter, number := make(chan bool), make(chan bool)
  letterDone := make(chan bool)
  go func() {
    i := 1
    for {
      select{
        case <-number: {
          fmt.Print(i)
          i++
          fmt.Print(i)
          i++
          letter <- true
          break
        }
        default: {
          break
        }
      }

    }
  }()

  go func(){
    i := 'A'
    for {
      if i > 'Z' {
        letterDone <- true
        return
      }
      select{
        case <-letter: {
          fmt.Print(string(i))
          i++
          fmt.Print(string(i))
          i++
          number <- true
          break
        }
        default: {
          break
        }
      }
    }
  }()
  number <- true
  <- letterDone
}