Optimization and refactoring of the maximum time calculation function

The task requires improving the structure and readability of the existing code responsible for calculating the maximum time needed for a set of devices to cover a given distance S. Below is the original C code fragment that needs to be analyzed and refactored for clarity while preserving its functionality.

/*
There are several devices, connected in chain like this:

start_idx---|
            |
D - D - D - A - A - A - A - B - B - D - D
            |-------- N --------|

The task is to get the speeds of N devices and calculate the maximum time to traverse some distance S.
*/

#define A 4
#define B 2

#define N A + B

// Function to get the speed of a device with index `idx`
double get_motor_speed(int idx);

static float counter = 0;

// Function to calculate the maximum time for the motors to traverse distance `S`
double calc_max_time(double S, int start_idx)
{
    double t[N];
    for (int i = 0, n = start_idx; i < N; i++, n++)
    {
        double v = get_motor_speed(n);
        counter += 1;

        if (v == 0)
            printf("error, can't divide by zero\n");
        else
        {
            printf("%f\n", S / v);
            t[i] = S / v;
        }
    }

    double result = 0;

    for (int i = 0; i < N; i++)
    {
        if (t[i] > result)
            result = t[i];
    }

    return result;
}

Requirements:

• Remove code duplication,
• Extract constants and calculations into separate functions/structures,
• Ensure clearer variable names and comments,
• Minimize the use of global state (counter).

The resulting code should be easier to maintain and test while preserving the original business logic.