%에 집중하라고하셔서
%2525 = %로 처리한코드

import java.util.Scanner;

public class Main {

    public static void main(String[] args) {
        // TODO Auto-generated method stub
        Scanner sc = new Scanner(System.in);
        int case_num = sc.nextInt();
        String Special_ch[] = { " ", "!", "", "", "$", "%", "", "", "(", ")", "*" };

        for (int loop = 0; loop < case_num; loop++) {
            String input_data = sc.nextLine();


            for (int i = 0; i < input_data.length() - 2; i++) {
                if (input_data.charAt(i) == '%'&&input_data.charAt(i+1) == '2') {
                    String str = Character.toString(input_data.charAt(i + 2));

                    int index = -1;

                    if (str.equals("a"))
                        index = 10;
                    else if(str.equals("0")|str.equals("1")|str.equals("4")|str.equals("5")|str.equals("8")|str.equals("9"))
                        index = Integer.parseInt(str);

                    if (index != -1) {
                        String converted = Character.toString(input_data.charAt(i));
                        converted += Character.toString(input_data.charAt(i + 1));
                        converted += Character.toString(input_data.charAt(i + 2));

                        String converting = Special_ch[index];
                        input_data = input_data.replace(converted, converting);
                        i=i-1;
                    }
                }
            }


            System.out.println(input_data);
        }

    }

}

와 %2525 를 %25로 처리한 코드

import java.util.Scanner;

public class Main {

    public static void main(String[] args) {
        // TODO Auto-generated method stub
        Scanner sc = new Scanner(System.in);
        int case_num = sc.nextInt();
        String Special_ch[] = { " ", "!", "", "", "$", "%", "", "", "(", ")", "*" };

        for (int loop = 0; loop < case_num; loop++) {
            String input_data = sc.nextLine();


            for (int i = 0; i < input_data.length() - 2; i++) {
                if (input_data.charAt(i) == '%'&&input_data.charAt(i+1) == '2') {
                    String str = Character.toString(input_data.charAt(i + 2));

                    int index = -1;

                    if (str.equals("a"))
                        index = 10;
                    else if(str.equals("0")|str.equals("1")|str.equals("4")|str.equals("5")|str.equals("8")|str.equals("9"))
                        index = Integer.parseInt(str);

                    if (index != -1) {
                        String converted = Character.toString(input_data.charAt(i));
                        converted += Character.toString(input_data.charAt(i + 1));
                        converted += Character.toString(input_data.charAt(i + 2));

                        String converting = Special_ch[index];
                        input_data = input_data.replace(converted, converting);
                    }
                }
            }


            System.out.println(input_data);
        }

    }

}

둘다 오답으로나오는데 어디가문제인가요 ㅠㅠ