求字符串的有序全排列

package main  
  
import (  
    "fmt"  
    "strconv"  
)  
  
func permutation(s string) []string {  
    if 1 == len(s) {  
        return []string{s}  
    }  
    var results []string  
    for i := 0; i < len(s); i++ {  
        rightPart := s[:i] + s[i+1:]  
        for _, j := range permutation(rightPart) {  
            result := string(s[i]) + j  
            results = append(results, result)  
        }  
    }  
    return results  
}  
  
func getPermutation(n int) []string {  
    s := ""  
    for i := 1; i <= n; i++ {  
        s += strconv.Itoa(i)  
    }  
    return permutation(s)  
}  
  
func main() {  
    fmt.Println(getPermutation(4))  
}