Judge correctness

#include <bits/stdc++.h>
using namespace std;
 
using type = unsigned short;
 
unsigned short mul[64][64];

struct Matrix {
    vector <vector <type> > data;
 
    int row() const { return data.size(); }
 
    int col() const { return data[0].size(); }
 
    auto & operator [] (int i) { return data[i]; }
 
    const auto & operator[] (int i) const { return data[i]; }
 
    Matrix() = default;
 
    Matrix(int r, int c): data(r, vector <type> (c)) { }
 
    Matrix(const vector <vector <type> > &d): data(d) {}
 
    friend ostream & operator << (ostream &out, const Matrix &d) {
        for (auto x : d.data) {
            for (auto y : x) out << y << ' ';
            out << '\n';
        }
        return out;
    }
 
    Matrix operator - (const Matrix &b) {
        Matrix a = *this;
        // assert(a.col() == b.col());
        // assert(a.row() == b.row());
        Matrix c(a.row(), a.col());
        for (int i = 0; i < a.row(); i++) {
            for (int j = 0; j < a.col(); j++) {
                c[i][j] = (a[i][j] - b[i][j] + 64) % 64;
            }
        }
        return c;
    }
 
    Matrix operator * (const Matrix &b) {
        Matrix a = *this;
        // assert(a.col() == b.row());
 
        Matrix c(a.row(), b.col());
        for (int i = 0; i < a.row(); ++i)
            for (int j = 0; j < b.col(); ++j)
                for (int k = 0; k < a.col(); ++k) {
                    c[i][j] += mul[a[i][k]][b[k][j]];
                    c[i][j] %= 64;
                }
        return c;
    }
};
 
mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());
int Rand(int l, int r) { return l + rng() % (r - l + 1); }
 
unsigned short decode(char c) {
    if (isupper(c)) return c - 'A';
    if (islower(c)) return 26 + c - 'a';
    if (isdigit(c)) return 52 + c - '0';
    if (c == '+') return 62;
    return 63; 
}
 
void solve() {
    int n;
    cin >> n;
    Matrix a(n, n), at(n, n), x(n, n);
    for (int i = 0; i < n; i++) {
        string tmp;
        cin >> tmp;
        for (int j = 0; j < n; j++) {
            char c = tmp[j];
            a[i][j] = decode(c);
            at[j][i] = decode(c);
        }
    }
    for (int i = 0; i < n; i++) {
        string tmp;
        cin >> tmp;
        for (int j = 0; j < n; j++) {
            char c = tmp[j];
            // cin >> c;
            x[i][j] = decode(c);
        }
    }
 
    // cout << a << '\n';
    // cout << at << '\n';
    // cout << (a * at) << '\n';
    // cout << x << '\n';
 
    int ite = 7;
    bool correct = true;
    while (ite--) {
        Matrix v(n, 1);
        for (int i = 0; i < n; i++) v[i][0] = Rand(0, 1);
 
        Matrix p = (a * (at * v)) - (x * v);
 
        for (int i = 0; i < n; i++) {
            if (p[i][0]) {
                correct = false;
                break;
            }
        }
 
        if (!correct) break;
    }
 
    cout << correct << '\n';
}
 
signed main() {
    cin.tie(0)->sync_with_stdio(0);
    
    for (int i = 0; i < 64; i++) {
        for (int j = 0; j < 64; j++) {
            mul[i][j] = (i * j) % 64;
        }
    }


    int t;
    cin >> t;
 
    while (t--) {
        solve();
    }
}

Test 1

Verdict: ACCEPTED

Test 2

Verdict: ACCEPTED

Test 3

Verdict: ACCEPTED

Test 4

Verdict: ACCEPTED

Test 5

Verdict: ACCEPTED

Test 6

Verdict: ACCEPTED

Test 7

Verdict: ACCEPTED

Test 8

Verdict: ACCEPTED

Test 9

Verdict: ACCEPTED

Test 10

Verdict: ACCEPTED