暑假一直没过，这次过了。。不易- -。10算两位数哦~

#include <iostream>
#include <math.h>

using namespace std;

#define M 50000

long long a[M], s[M];

void init() {
	a[1] = s[1] = 1;
	for (int i = 2; i < M; i++) {
		a[i] = a[i - 1] + (int)(log10((double)i) + 1);
		s[i] = s[i - 1] + a[i];
	}
}

int solve(int x) {
	int i = 1;
	while (s[i] < x)
		i++;
	int pos = x - s[i - 1];
	int len = 0;
	for (i = 1; len < pos; i++)
		len += (int)log10(i*1.0) + 1;
	return (i - 1) / (int)pow((double)10, (len - pos)) % 10;
}

int main() {
	int t;
	init();
	cin>>t;
	while (t--) {
		int n;
		cin>>n;
		cout << solve(n) << endl;
	}
}

poj1019