deque와 맨앞 요소만 책임지는 front배열을 두어 운용했습니다. import sys input = sys.stdin.readline from collections import deque N = int(input()) a = list(map(int, input().split()))[::-1] floor = [i for i in range(N, 1, -1)] front = [1] q = deque() for command in a[1:]: if command == 1: q.appendleft(front.pop()) front.append(floor.pop()) elif command == 2: q.appendleft(floor.pop()) else: q.append(floor.pop()) answer ..