以下是我写的相当丑陋的代码，不要鄙视
#include	<stdio.h>

typedef unsigned long long ull;
static const int arrsize = 32000;
unsigned long long skCount[arrsize];
unsigned long long totalCount[arrsize];

int findDigitNo(int n)
{
    int count = 0;
    if (n == 0)
        return 1;
    while (n) {
        ++count;
        n /= 10;
    }
    return count;
}

int findLimit()
{
    skCount[0] = totalCount[0] = 0;
    skCount[1] = 1;
    totalCount[1] = 1;
    int i;
    for (i = 2; i < arrsize; ++i)
    {
        int digitNo = findDigitNo(i);
        skCount[i] = skCount[i-1] + digitNo;
        totalCount[i] = totalCount[i-1] + skCount[i];
        if (totalCount[i] >= 2147483647)
            break;
    }
    return i;
}

//TODO: arr add 0
// left <= x < right
int binarySearchTotal(int l, int h, ull x)
{
    h = h + 1;
    while (l + 1 < h) {
        int mid = (l+h) / 2;
        if (x < totalCount[mid])
            h = mid;
        else 
            l = mid;
    }
    return l;
}

int binarySearchSk(int l, int h, ull x)
{
    h = h + 1;
    while (l + 1 < h) {
        int mid = (l+h) / 2;
        if (x < skCount[mid])
            h = mid;
        else 
            l = mid;
    }
    return l;
}

int digitArr[8];
int findDigitsNo(int n)
{
    int count = 0;
    if (n == 0)
        return 1;
    while (n) {
        digitArr[count++] = n % 10;
        n /= 10;
    }
    return count;
}

int main(int argc, char *argv[])
{
    int T;
    int highLimit = findLimit();
    char digitch;
    
    while (scanf("%d", &T) == 1)
    {
        while (T--) {
            ull pos;
            scanf("%llu", &pos);
            int idx = binarySearchTotal(1, highLimit, pos);
            if (pos == totalCount[idx])
                digitch = '0' + idx % 10;
            else {
                ull remain = pos  - totalCount[idx];
                int skidx = binarySearchSk(1, idx+1, remain);
                if (remain == skCount[skidx])
                    digitch = '0' + skidx % 10;
                else 
                {
                    ull rr = remain - skCount[skidx];
                    int digitcount = findDigitsNo(skidx+1);
                    digitch = '0' + digitArr[digitcount-rr];
                }
            }
            printf ( "%c\n", digitch);
        }
    }
}