각 ID별 신고자를 set에 저장 후(중복신고 제약조건), 정지 대상일 경우 신고자의 mail 수를 증가
def solution(id_list, report, k):
# init
answer = [0 for _ in range(len(id_list))]
id_reports = dict()
id_index = dict()
index = 0
for id in id_list:
id_reports[id] = set()
id_index[id] = index
index += 1
x = list(map(lambda x: x.split(), report))
for [reporter, target] in list(map(lambda x: x.split(), report)):
id_reports[target].add(reporter)
for id, reports in id_reports.items():
if len(reports) >= k:
for reporter in reports:
answer[id_index[reporter]] += 1
return answer