BOJ - 1874 - 스택 수열

def solution():
    
    N = int(input())
    data = []
    Stack = []
    ret = []

    for _ in range(N):
        data.append(int(input()))

    idx = 0
    
    for i in range(1, (N+1)):
        Stack.append(i)
        ret.append('+')

        while Stack and Stack[len(Stack) - 1] == data[idx]:
            Stack.pop()
            idx += 1
            ret.append('-')
            
    if Stack:
        print('NO')
    else:
        for i in ret:
            print(i)
solution()

https://www.acmicpc.net/problem/1874