실패율 (list.count() 함수)

def solution(N, stages):
    result = {}
    a = len(stages)
    for i in range(1,N+1):
        if a != 0:
            cnt = stages.count(i) # stages에서 i의 개수
            result[i] = cnt/a
            a-=cnt
        else:
            result[i] = 0

    return sorted(result, key=lambda x: result[x], reverse=True)

def solution(N, stages):
    answer = []
    
    a = [0] * (N+1)
    for x in stages:
        a[x - 1] += 1
        
    b = {}
    for i in range(N):
        if sum(a[i:]) != 0:
            b[i+1]=a[i]/sum(a[i:])
        else:
            b[i+1]=0

    b = sorted(b.items(), key=lambda x: x[1], reverse=True)

    for x in b:
        answer.append(x[0])
        
    return answer