[Baekjoon Online Judge] 1874 - 스택 수열 / Java

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

1874번: 스택 수열

import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.util.Stack;

public class Main {

	public static void main(String[] args) throws Exception {
		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
		StringBuilder sb = new StringBuilder();
		Stack<Integer> stack = new Stack<Integer>();

		int N = Integer.parseInt(br.readLine());

		int j = 1;
		A: for (int i = 0; i < N; i++) {
			int n = Integer.parseInt(br.readLine());

			while (true) {
				if (n >= j) {
					stack.push(j++);
					sb.append("+").append("\n");
				}

				if (!stack.isEmpty()) {
					if (stack.peek() == n) {
						stack.pop();
						sb.append("-").append("\n");
						break;
					} else if (stack.peek() > n) {
						System.out.println("NO");
						sb.delete(0, sb.length());
						break A;
					}
				}
			}
		}
		System.out.println(sb);
	}
}