[프로그래머스/Python] 실패율

코딩테스트 연습 - 실패율

import operator
def solution(N, stages):
    failure = {}
    for i in range(1, N+1):
        nominator=0
        denominator=0
        for j in stages:
            if j == i:
                nominator += 1
                denominator += 1
            if j > i:
                denominator += 1     
        if denominator == 0:
            failure[i] = 0
        else:
            failure[i] = (nominator/denominator)
        
    failure = sorted(failure.items(), key=lambda x: (-x[1], x[0]))
    
    return [i[0] for i in failure]