[Programmers] 숫자 짝꿍

Python

def solution(X, Y):
    answer = ""
    for i in range(9,-1,-1) :
        answer += (str(i) * min(X.count(str(i)), Y.count(str(i))))

    if not answer:
        answer = "-1"
    elif answer[0] == "0":
        answer = "0"

    return answer