Zadacha2

#include <iostream>
#include <cmath>
#define EPS 0.001

using namespace std;

bool func(double a[], int& n, double b[], int& nb);

int main()
{
    int n, nb;
    cout << "Enter count: ";
    cin >> n;
    double a[n], b[n];
    cout << "Enter numbers: ";
    for (int i = 0; i < n; i++)
    {
        cin >> a[i];
    }

    bool isGeometricProg = func(a, n, b, nb);

    cout << "Arithmetic progression: ";
    for (int i = 0; i < n; i++)
    {
        cout << a[i] << " ";
    }
    cout << endl;
    cout << "Filtered elements (FE): ";
    for (int i = 0; i < nb; i++)
    {
        cout << b[i] << " ";
    }
    cout << endl;

    cout << boolalpha << "Is geometric progression (FE): " << isGeometricProg << endl;
    return 0;
}

bool func(double a[], int& n, double b[], int& nb)
{
    double prevG, q;
    int cntExtract = 0;
    bool isGeom = true;

    double d = a[1] - a[0];
    int j = 2;

    for (int i = 2; i < n; i++)
    {
        if (fabs(a[j - 1] + d - a[i]) < EPS)  // a[j - 1] + d == a[i]
        {
            a[j] = a[i];
            j++;
        }
        else
        {
            b[cntExtract] = a[i];
            cntExtract++;
            if (cntExtract == 1)
            {
                prevG = a[i];
            }
            else if (cntExtract == 2)
            {
                q = a[i] / prevG;
                prevG = a[i];
            }
            else
            {
                if (!(fabs(prevG * q - a[i]) < EPS)) // prevG * q != a[i]
                {
                    isGeom = false;
                }
                prevG = a[i];
            }
        }
    }
    n = j;
    nb = cntExtract;
    if (cntExtract < 2)
    {
        return false;
    }
    return isGeom;
}