Python

likeyoutubeID.py

ALPHABET = "bcdfghjklmnpqrstvwxyz0123456789BCDFGHJKLMNPQRSTVWXYZ"
BASE = len(ALPHABET)
MAXLEN = 6

def encode_id(self, n):

    pad = self.MAXLEN - 1
    n = int(n + pow(self.BASE, pad))

    s = []
    t = int(math.log(n, self.BASE))
    while True:
        bcp = int(pow(self.BASE, t))
        a = int(n / bcp) % self.BASE
        s.append(self.ALPHABET[a:a+1])
        n = n - (a * bcp)
        t -= 1
        if t < 0: break

    return "".join(reversed(s))

def decode_id(self, n):

    n = "".join(reversed(n))
    s = 0
    l = len(n) - 1
    t = 0
    while True:
        bcpow = int(pow(self.BASE, l - t))
        s = s + self.ALPHABET.index(n[t:t+1]) * bcpow
        t += 1
        if t > l: break

    pad = self.MAXLEN - 1
    s = int(s - pow(self.BASE, pad))

    return int(s)