Initialize Filter3 Class

#include <iostream>
using namespace std;

// Define Filter3 class here

class Filter3
{
    private:
    const int id;
    int coeff[3];
    int lastOutput;

    public:
    Filter3(int filterId, int c0, int c1, int c2) noexcept : 
                                                                    id(filterId), 
                                                                    coeff{c0 , c1 , c2},
                                                                    lastOutput(0)
                                                                    {};
    void apply( int x) noexcept
    {
        lastOutput = x * coeff[0] + coeff[1] + coeff[2];
    }

    int read() const noexcept
    {
        return lastOutput;
    }
};
int main() {
    int id, c0, c1, c2;
    cin >> id >> c0 >> c1 >> c2;

    Filter3 f(id, c0, c1, c2);

    int s1, s2;
    cin >> s1 >> s2;

    f.apply(s1);
    f.apply(s2);

    cout << f.read();
    return 0;
}

Solving Approach