请你帮帮我解一下这道题吧

int main() {
    int n;
    scanf("%d", &n);
    double* avg = (double*)malloc(sizeof(double*)*n);
    for (int i = 0; i < n; i++)
    {
            char arr[3];
            scanf("%s", &arr[0]);
            for (int k = 0; k < 3; k++)
            {
                if (arr[k] >= '0'&&arr[k] <= '9')
                    arr[k] -= 48;
            }
            avg[i] = (arr[0] + arr[1] + arr[2]) / 3.0;
    }
    for (int i = 0; i <n; i++)
        printf("%.2f\n", avg[i]);

    free(avg);
    //system("pause");
    return 0;
}