面试题：如何并发地打印1-9，最后打印10。

1 go for 2 defer ???

for循环1-9启goroutine打印, 用chan或者waitgroup保持同步, 完成之后打印10

package main import ( "fmt" "sync" ) func main() { wg := sync.WaitGroup{} wg.Add(1) go func() { defer wg.Done() var j int for i := 1; i < 10; i++ { fmt.Println(i) j = i + 1 } fmt.Println(j) }() wg.Wait() }