golang實現base62編碼

package main

import (
    "fmt"
    "math"
)

var base = []string {"a","b","c","d","e","f","g","h","i","j","k","l","m","n","o","p","q","r","s","t","u","v","w","x","y","z","A","B","C","D","E","F","G","H","I","J","K","L","M","N","O","P","Q","R","S","T","U","V","W","X","Y","Z","1","2","3","4","5","6","7","8","9","0"}

func base62encode(num int) string {
    baseStr := ""
    for {
        if num <= 0 {
            break
        }

        i := num % 62
        baseStr += base[i]
        num = (num - i) / 62
    }
    return baseStr
}

func base62decode(base62 string) int {
    rs := 0
    len := len(base62)
    f := flip(base)
    for  i := 0; i < len; i++ {
        rs += f[string(base62[i])] * int(math.Pow(62, float64(i)))
    }
    return rs
}

func flip(s []string) map[string]int {
    f := make(map[string]int)
    for index, value := range s {
        f[value] = index
    }
    return f
}

func main() {
    m := base62encode(12645354)
    fmt.Println(m)
    fmt.Println(base62decode(m))
}