https://programmers.co.kr/learn/courses/30/lessons/42862
다른 사람 코드 참고
def solution(n, lost, reserve):
answer = 0
set_reserve=set(reserve)-set(lost)
set_lost=set(lost)-set(reserve)
for i in set_reserve:
if i-1 in set_lost:
set_lost.remove(i-1)
elif i+1 in set_lost:
set_lost.remove(i+1)
answer=n-len(set_lost)
return answer
set_reserve=set(reserve)-set(lost)
와 set_lost=set(lost)-set(reserve)
를 하여 중복 제거>>> s1 = set([1,2,3])
>>> s1
{1, 2, 3}
>>> s2 = set("Hello")
>>> s2
{'e', 'H', 'l', 'o'}