Kyselyt

#include <iostream>
#include <string>

using namespace std;

int pow(int a, int b)
{
	if (b == 0) return 1;
	int t = a;
	for (int i = 1; i < b; i++)
		t *= a;
	return t;
}

int nums(int n)
{
	if (n == 0)
		return 0;
	else if (n == 1)
		return 9;
	else
		return ((pow(10, n) - 1) - (pow(10, n - 1) - 1)) * n + nums(n - 1);
}

char at(int x)
{
	int i = 0;
	while (x - nums(i) > 0) i++;
	x -= nums(i - 1);
	int p = x - 1;
	x = p / i;
	x += pow(10, i - 1);
	string n = to_string(x);
	return n[p % i];
}

int main()
{
	int q;
	cin >> q;
	for (int i = 0; i < q; i++)
	{
		int x;
		cin >> x;
		cout << at(x) << '\n';
	}
	return 0;
}

Test 1

Group: 1

Verdict: ACCEPTED

Test 2

Group: 2

Verdict: ACCEPTED

Test 3

Group: 3

Verdict: WRONG ANSWER