Kyselyt

#include <iostream>
#include <cmath>
#include <cstring>
#include <cstdlib>
#include <cstdlib>

using namespace std;
typedef long long ll;

ll
decade(ll n, ll *sum)
{
	*sum = 0;
	for (int i = 1; i < 1000000; i++) {
		if (*sum + i*9*pow(10.0, i-1) > n)
			return i;
		else
			*sum += i*9*pow(10.0, i-1);
	}
	return 0;
}
ll
nnum(ll dec, ll nth)
{
	return (ll)(pow(10.0, (int)dec-1)-1+nth);
}


int dig(int a, int b) {
	return (int)(a / pow(10.0, b)) % 10;
 }

int
main(int argc, char **argv)
{
	ios_base::sync_with_stdio(0);
	cin.tie(0);
	int q;
	cin >> q;
	ll qs[q];
	for (int i = 0; i < q; i++) {
		cin >> qs[i];
		if (qs[i] < 10) {
			cout << qs[i] << "\n";
		} else {
			ll inth, nth, dec, s, sm, num;
			
			dec = decade(qs[i], &s);
			sm = qs[i] - s;
			nth = (ll)ceil((double)sm/(double)dec);
			num = nnum(dec, nth);
			inth = (sm-1) % dec;
			cout << dig(num, inth) << "\n";
		}
	}
	return 0;
}

Test 1

Group: 1

Verdict: WRONG ANSWER

Test 2

Group: 2

Verdict: WRONG ANSWER

Test 3

Group: 3

Verdict: WRONG ANSWER