Binary Strings Yet Again

#include <bits/stdc++.h>
using namespace std;
using ll = signed long long;
template<typename T = int> T nxt(){T x_; cin >> x_; return x_;}

int main() 
{
    ios::sync_with_stdio(false), cin.tie(0);

    int cases;

    for(cin >> cases; cases--;)
    {
        int n, m;
        cin >> n >> m;
        int T[m], nn = n;
        bitset<30> A[m];
        for(auto &b : T) cin >> b;
        for (int i = 0; i < m; i++)
            A[i] = T[i];
        
        ll val = 0, zz = (int) A[m - 1].count() - 30;
        for(auto &b : A) zz += 30 - (int) b.count();
        for (int b = 0; b < 30; b++)
            if(A[m - 1][b] == 0 && (m - 1) * 30 + b < n)
                zz++;
        
        vector<int> D;
        for (int i = 2; i * i <= nn; i++) if(nn % i == 0) {
            D.push_back(i);
            while (nn % i == 0)
                nn /= i;
        } if(nn > 1) D.push_back(nn);

        for(auto &a : D) {
            array<int, 2> cc = {0, 0};
            ll res = 0, temp = 0, zzz = zz;
            int zero_cnt[a + 1] = {0}, all_one = 0, j = 0;
            for (int i = 0; i < n; i++) {
                bool bit = A[i / 30][j++];
                temp += (ll) cc[0] * bit;
                cc[bit]++;
                if((i + 1) % a == 0) {
                    res += temp + (ll) zero_cnt[cc[1]] * cc[1];
                    if(cc[1] == a) all_one += a; 
                    zero_cnt[cc[1]] += cc[0];
                    cc = {0, 0}, temp = 0;
                }
                if(j == 30) j = 0;
            }
            res += zzz * all_one;
            for (int i = a - 1; i > 0; i--) {
                zzz -= zero_cnt[i];
                res += zzz * i * zero_cnt[i] / (a - i);
            }
            val = max(val, res);
        }
        cout << val << '\n';
    }
    //Struggling!!! read question once again...
}