Weekly group assignment algorithm

Round-robin algorithm will do the trick i think.

Add the remaining student to the second group and you are done.

First run
1   2   3   4   5   6   7   8   9   10  11  12
23  22  21  20  19  18  17  16  15  14  13

Second run
1   23  2   3   4   5   6   7   8   9   10  11  
22  21  20  19  18  17  16  15  14  13  12

...