3진법 뒤집기

def solution(n):
    answer = ""
    while True:
        div, mod = divmod(n, 3)
        if div == 0:
            answer += str(mod)
            break
        else:
            answer += str(mod)
            n = div
    ret = 0
    for i in range(len(answer)):
        ret = ret * 3 + int(answer[i])
    return ret