```go
package main
import (
"log"
"time"
)
var myMap = make(map[int64]int64)
// 计算阶乘
func factorial(n int64) int64 {
if n == 0 {
return 1
}
var i int64 = 1
var res int64 = 1
for ; i <= n; i++ {
res *= i
}
return res
}
func putMap(n int64) {
myMap[n] = factorial(n)
}
func main() {
for i := 1; i <= 20; i++ {
go putMap(int64(i))
}
time.Sleep(3 * time.Second)
// 遍历map
for i, v := range myMap {
log.Println(i, v)
}
}
```
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