124 나라의 숫자.py

#역시 재귀는 어렵다. 
'''
def solution(a):  
    answer = '' 
    def div(a):
        nonlocal answer
        if a == 0:
            return answer[::-1]
        if a % 3 == 0:
            answer += '4'
            return div(a//3 - 1)
        if a % 3 == 1:
            answer += '1'
            return div(a//3)
        if a % 3 == 2:
            answer += '2'
            return div(a//3)
    return div(a)
'''

def solution(n):
    result = []
    while n:
        t = n % 3
        if not t:
            t = 4
            n -= 1
        result.append(str(t))
        n //= 3
    return ''.join(result[::-1])