문제 링크

정답 :

def solution(arr):
    answer = []
    check = arr.count(2)
    cnt = 0
    
    if check == 0:
        return [-1]
    elif check == 1:
        return [2]
    
    for i in arr:
        if i == 2:
            cnt += 1
        if cnt >= 1:
            if check == cnt:
                answer.append(i)
                return answer
            answer.append(i)

방법 1.

def solution(arr):
    answer = []
    check=[]
    if 2 not in arr:
        return [-1]
    else:
        for i in range(0, len(arr)):
            if arr[i]==2:
                check.append(i)
    return arr[check[0]:check[-1]+1]

방버 2.

def solution(arr):
    if 2 not in arr:
        return [-1]
    return arr[arr.index(2) : len(arr) - arr[::-1].index(2)]