题解 | #多组_带空格的字符串_T组形式#

import java.util.Scanner;

// 注意类名必须为 Main, 不要有任何 package xxx 信息
public class Main {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        int t = scanner.nextInt();
        while (t > 0) {
            int n = scanner.nextInt();
            scanner.nextLine(); // 消耗掉上一行输入后的换行符
            String s = scanner.nextLine();
            StringBuilder noSpaceStr = new StringBuilder();
            for (int i = 0; i < n; i++) {
                if (s.charAt(i) != ' ') {
                    noSpaceStr.append(s.charAt(i));
                }
            }
            StringBuilder reversed = new StringBuilder(noSpaceStr).reverse();
            System.out.println(reversed.toString());
            t--;
        }
        scanner.close();
    }
}