HackerRank: Encryption

HackerRank: Encryption
An English text needs to be encrypted. The encryption algorithm first removes the spaces from the text and then the characters are written into a rectangle (or a square), whose width and height have the following constraints:

floor(sqrt( len(word) )) <= width, height <= ceil(sqrt( len(word) ))
In case of a rectangle, the number of rows will always be smaller than the number of columns.

Also ensure, height * width >= len(word)

If multiple rectangles satisfy the above conditions, choose the one with the minimum area.
The encoded message is obtained by displaying the characters in a column, inserting a space, and then displaying the next column and inserting a space and so on.For example, the encoded message for the above rectangle is:

imtgdvs fearwer mayoogo anouuio ntnnlvt wttddes aohghn sseoau

You will be given a message in English with no spaces between the words.The maximum message length can be 81 characters. Print the encoded message.

int main()
{
    string str;
    cin >> str;
    int len = (int)str.size();
    int lb = (int)sqrt(1.0*len);
    int ub = (int)ceil(sqrt(1.0*len));
    int ans = INT_MAX;
    int r = 0, c = 0;
    for (int row = lb; row <= ub; row++)
        for (int col = row; col <= ub; col++)
            if (row * col >= len && row * col < ans)
            {
                ans = row * col;
                r = row;
                c = col;
            }
    for (int i = 0; i < c; i++)
    {
        for (int j = 0; j < r; j++)
            if (j*c + i < len)
                cout << str[j*c + i]; 
        cout << " ";
    }
    cout << endl;
    return 0;
}