marker

마커는 단일 시행(단일 경우)에 쌍으로 따라붙음

import java.util.Scanner;
import java.util.Stack;

public class Main {
    public static void main(String[] args) {

        // ISC - L1
        Scanner sc = new Scanner(System.in);
        int N = sc.nextInt();

        // L2 ~
        int[] A = new int[N];
        for (int i = 0; i < N; i++) {
            A[i] = sc.nextInt();
        }

        Stack<Integer> stack = new Stack<>();
        StringBuffer marker = new StringBuffer();
        int num = 1;
        boolean possibility = true;

        for (int i = 0; i < A.length; i++) {
            if (num <= A[i]) {

                while (num <= A[i]) {
                    stack.push(num++);
                    marker.append("+\n");
                }

                stack.pop();
                marker.append("-\n");

            } else {
                int n = stack.pop();
                if (n > A[i]) {
                    System.out.println("NO");
                    possibility = false;
                    break;
                } else {
                    marker.append("-\n");
                }
            }
        }
        if (possibility)
            System.out.println(marker.toString());
    }
}