(Problem 40)Champernowne's constant

An irrational decimal fraction is created by concatenating the positive integers:

0.123456789101112131415161718192021...

It can be seen that the 12^th digit of the fractional part is 1.

If d_n represents the n^th digit of the fractional part, find the value of the following expression.

d₁  d₁₀  d₁₀₀  d₁₀₀₀  d₁₀₀₀₀  d₁₀₀₀₀₀  d_1000000

#include <stdio.h>

int solve()
{
    int i, k, result, n, t, temp;
    int s[], a[];
    i = k = ;
    n = result = ;
    t = ;
    while() {
        temp = n;
        i = ;
        while(temp) {
            s[i++] = temp % ;
            temp /= ;
        }
        i--;
        while(i >= ) {
            a[k] = s[i];
            t++;
            if(t ==  || t ==  || t ==  || t ==  || t ==  || t ==  || t == ) {
                result *= a[k];
                if(t == )  return result;
            }
            if(k == ) {
                k = ;
            } else {
                k++;
            }
            i--;
        }
        n++;
    }
}

int main(void)
{
    printf("%d\n",solve());
    return ;
}

Answer:

210