string encryption(string s) {
    int L = s.size();

    int rows = floor(sqrt(L));
    int cols = ceil(sqrt(L));
    if (rows * cols < L) {
        rows = cols;
    }

    vector<string> result;
    for (int c = 0; c < cols; c++) {
        string word = "";
        for (int r = 0; r < rows; r++) {
            int idx = r * cols + c;
            if (idx < L) {
                word += s[idx];
            }
        }
        result.push_back(word);
    }

    string encoded = "";
    for (int i = 0; i < result.size(); i++) {
        if (i > 0) encoded += " ";
        encoded += result[i];
    }

    return encoded;
}