48. Rotate Image

You are given an n x n 2D matrix representing an image.

Rotate the image by 90 degrees (clockwise).

Follow up:
Could you do this in-place?

void rotate(vector<vector<int>>& matrix) {
    int n = matrix.size(), i, j, k, t, x, y, tx;
    for(i = 0; i <= n>>1; i++)
    {
        for(j = i; j < n-1-i; j++)
        {
            t = matrix[i][j];
            x = i; y = j;
            for(k = 0; k < 3; k++)
            {
                matrix[x][y] = matrix[n-1-y][x];
                tx = x;
                x = n-1-y;
                y = tx;
            }
            matrix[x][y] = t;
        }
    }
}