[Python][프로그래머스][Level3] 여행경로

answer=[]
def dfs(start,check,tickets,ans):
    if not 0 in check:
        answer.append(ans)
        return
    
    for idx, (x, y) in enumerate(tickets):
        if x==start and check[idx]==0:
            check[idx]=1
            dfs(y,check,tickets,ans+[y])
            check[idx]=0
    
def solution(tickets):
    dfs("ICN",[0]*len(tickets),tickets,["ICN"])
    return sorted(answer)[0]