Kyselyt

#include <iostream>
#include <sstream>

char f(unsigned long long k) {
	int w = 1;
	unsigned long long a = 1;
	k -= 1;
	while (true) {
		if (k / w < 9 * a) {
			std::ostringstream s;
			s << (a + k / w);
			return s.str()[k % w];
		}
		k -= 9 * a * w;
		a *= 10;
		w += 1;
	}
}

int main() {
	int q;
	std::cin >> q;
	for (int i = 0; i < q; ++i) {
		unsigned long long k;
		std::cin >> k;
		std::cout << f(k) << '\n';
	}
}

Test 1

Group: 1

Verdict: ACCEPTED

Test 2

Group: 2

Verdict: ACCEPTED

Test 3

Group: 3

Verdict: ACCEPTED