Digit Queries [Brute Force]

#include <bits/stdc++.h>
using namespace std;

#define INF 1e9

// find number at index n in "0123456789101112131415..."

int main() {
    int n; scanf("%d", &n);

    if(n >= 0 && n<=10){
        printf("%d", n-1);
        return 0;
    }

    int cnt = 11;
    for (int i = 10; i <= n; i++) // iterative solution
    {
        int k = i, d = 0;
        while(k) k/=10, d++;
        d = pow(10, d-1);
        k = i;

        while(d){
            int x = k / d;
            if(cnt == n){
                printf("%d", x);
                return 0;
            }

            k -= x*d;
            d /= 10;
            cnt++;
        }
    }

    return 0;
}