Kyselyt

#include <stdio.h>

unsigned solve(long long unsigned n) {
	long long unsigned first = 1;
	long long unsigned last = 9;
	long long unsigned length = 1;
	while (n >= (last - first + 1) * length) {
		n -= (last - first + 1) * length;
		++length;
		first = last + 1;
		last = last * 10 + 9;
	}

	long long unsigned k = first + n / length;
	n %= length;
	for (n = length - n - 1; n--; k /= 10);
	return k % 10;
}

int main(void) {
	unsigned q;
	if (scanf("%u", &q) != 1) {
		return 1;
	}
	for (long long unsigned k; scanf("%llu", &k) == 1;) {
		printf("%u\n", solve(k - 1));
	}
}

Test 1

Group: 1

Verdict: ACCEPTED

Test 2

Group: 2

Verdict: ACCEPTED

Test 3

Group: 3

Verdict: ACCEPTED