Kyselyt

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++) {
            Long index = input.nextLong();
            if (index < 10) {
                System.out.println(index);
            }
            else {
                long base = 10;
                long len = 2;
                while (true) {
                    if (index < base) {
                        len = len - 1;
                        base = base - (9 * len * (long) Math.pow(10, len - 1));
                        break;
                    }
                    base = base + (9 * len * (long) Math.pow(10, len - 1));
                    len = len + 1;
                }
                //System.out.println("Base: " + base + ", Length: " + len);
                Long diff = (index - base);
                //System.out.println("Diff: " + diff);
                Long pos = (diff % len);
                //System.out.println("Position: " + (pos + 1) + "/" + len);
                Long step = len * (long) Math.pow(10, len - pos - 1);
                //System.out.println("Step: " + step);
                if (pos == 0) {
                    System.out.println((1 + Math.floorDiv(diff, step)) % 10);
                }
                else {
                    System.out.println((Math.floorDiv(diff, step)) % 10);
                }
            }
        }
    }
}

Test 1

Group: 1

Verdict: ACCEPTED

Test 2

Group: 2

Verdict: ACCEPTED

Test 3

Group: 3

Verdict: ACCEPTED