gistfile1.go

package main
 
import (
  "crypto/sha1"
  "fmt"
  "io"
  "bytes"
  "os"
  "bufio"
  "os/exec"
)
 
func sha(str string) string {
  h := sha1.New()
  io.WriteString(h, str)
  
  return fmt.Sprintf("%x", h.Sum(nil))
}
 
// writeLines writes the lines to the given file.
func writeLines(line string, path string) error {
  file, err := os.Create(path)
  if err != nil {
    return err
  }
  defer file.Close()

  w := bufio.NewWriter(file)
  fmt.Fprintln(w, line)
  return w.Flush()
}

func main(){
  cmd := exec.Command("git", "write-tree")
    tree, err := cmd.Output()
    if err != nil {
        fmt.Println(err)
        return
    }
    fmt.Printf("%s", tree)
 
    cmd = exec.Command("git", "rev-parse", "HEAD")
    parent, err := cmd.Output()
    if err != nil {
        fmt.Println(err)
        return
    }
    fmt.Printf("%s", parent)
  s := `tree %s
parent %s
author CTF user <me@example.com> 1390424498 +0000
committer CTF user <me@example.com> 1390424498 +0000
 
Give me a Gitcoin
 
%d
 
`
  counter := 0
  for {
    hash := sha(fmt.Sprintf(s, tree, parent, counter))
    if bytes.Compare([]byte(hash), []byte("ff")) < 0{
      fmt.Println(counter)
      break
    }
    counter++
  }

  writeLines(fmt.Sprintf(s, tree, parent, counter), "output.txt")

}