main.go

/*
     *
    ***
   *****
  *******
 *********
***********
 *********
  *******
   *****
    ***
     *
*/
package main

import (
	"fmt"
)

func replaceStr(ch string, n int) string{
	txt := ""
	for i:=0; i<n;i++{txt+=ch}
	return txt
}
func genLevel(level int) string{
	txt := ""
	ch := " "
	star := "*"
	for i:=0;i< level; i++ {
		n := level - i	
		s := (i*2)+1
		txt += replaceStr(ch, n)+replaceStr(star, s)
		txt += "\n"
	}
	for i:=level;i>=0 ; i-- {
		n := level - i	
		s := (i*2)+1
		txt += replaceStr(ch, n)+ replaceStr(star, s)
		txt += "\n"
	}
	return txt
}

func main() {
	fmt.Println(genLevel(5))
}