[백준] 1874[Swift]

import Foundation

var stack: [Int] = []
var result: [String] = []
var count = 1
for _ in 1...Int(readLine()!)! {
let num = Int(readLine()!)!

while count <= num {
    result.append("+")
    stack.append(count)
    count += 1
}

if stack.last! == num {
    stack.popLast()
    result.append("-")
} else {
    print("NO")
    exit(0) 
}

}

print(result.joined(separator: "\n"))