Kyselyt

import java.math.BigInteger;
import java.util.Scanner;

public class Kyselyt {
    public static void main(String[] args) {
        Scanner input = new Scanner(System.in);
        int q = input.nextInt();
        for (int i = 0; i < q; i++) {
            int index = input.nextInt();
            if (index < 10) {
                System.out.println(index);
            }
            else {
                int base = 10;
                int len = 2;
                while (true) {
                    if (index < base) {
                        len = len - 1;
                        if (len == 2) {
                            base = base - (90 * len);
                        }
                        else {
                            base = base - (100 * len);
                        }
                        break;
                    }
                    if (len == 2) {
                        base = base + (90 * len);
                    }
                    else {
                        base = base + (100 * len);
                    }
                    len = len + 1;
                }
                BigInteger value = new BigInteger("10");
                System.out.println(base + ", " + len + ", " + index);
                System.out.println(value.pow(len - 1).add(new BigInteger(Integer.toString(Math.floorDiv(index - base, len)))).toString().charAt((index - (base % len)) % len)); //+ Math.floorDiv(index - base, len)).charAt((index - (base % len)) % len);
            }
        }
    }
}

Test 1

Group: 1

Verdict: WRONG ANSWER

Test 2

Group: 2

Verdict: WRONG ANSWER

Test 3

Group: 3

Verdict: RUNTIME ERROR

Exception in thread "main" java.util.InputMismatchException: For input string: "672274832941907421"
	at java.util.Scanner.nextInt(Scanner.java:2123)
	at java.util.Scanner.nextInt(Scanner.java:2076)
	at Kyselyt.main(Kyselyt.java:9)