Given vector<vector<int>> with the same number of rows, return a vector that places them side by side in the following pattern:

   a[0][0] a[0][1] ... a[0][n] b[0][0] b[0][1] ... b[0][m]
   a[1][0] a[1][1] ... a[1][n] b[1][0] b[1][1] ... b[1][m]

Note: the supplied vectors for this problem are not necessarily rectangular.