Sieve a list picking up the elements repeated a certain number of times

sieveOfRepeated.cpp

// sieveOfRepeated.cpp
// juanfc 2023-11-27
// https://gist.github.com/079916adc1420f95017328d1f04797e7

#include <iostream>
#include <array>
using namespace std;

const int MAX = 100;
struct TOpenAr {
    int n;
    array<int, MAX> ar;
};

TOpenAr sieve(TOpenAr a, int reps);
void print(TOpenAr a);

int main()
{
    TOpenAr a = {9, {{1,3,4,3,1,3,0,-6,4}}};
    print(sieve(a, 2));
    a = (TOpenAr){5, {{1,2,3,4,5}}};
    print(sieve(a, 1));
    a = (TOpenAr){0, {{}}};
    print(sieve(a, 2));
    return 0;
}

int count(TOpenAr a, int x);

TOpenAr sieve(TOpenAr a, int reps)
{
    TOpenAr r;
    r.n = 0;
    for (int i = 0; i < a.n; ++i)
        if (count(a, a.ar[i]) == reps and count(r, a.ar[i]) == 0)
            r.ar[r.n++] = a.ar[i];
    return r;
}

int count(TOpenAr a, int x)
{
    int cnt = 0;
    for (int i = 0; i < a.n; ++i)
        if (a.ar[i] == x)
            ++cnt;
    return cnt;
}

void print(TOpenAr a)
{
    for (int i = 0; i < a.n; ++i)
        cout << a.ar[i] << " ";
    cout << endl;
}