백준 1874번: 스택 수열

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

해설

"""
1 2 3 4 (PUSH)   STACK:
1 2 (POP)        STACK: 4 3
1 2 5 6 (PUSH)   STACK:
1 2 5 (POP)      STACK: 4 3 6
1 2 5 7 8 (PUSH) STACK:
(POP)            STACK: 4 3 6 8 7 5 2 1
"""
count = 1 
n = int(input()) 

stack = []
ans = []
define = True

for _ in range(n):
  num = int(input())

  while count <= num:
    stack.append(count)
    ans.append('+')
    count += 1
      
  if stack[-1] == num:
    stack.pop()
    ans.append('-')
  else:
    define = False
    
if define == True:
  for c in ans:
    print(c)

else:
  print("NO")