Write a program to group the ...

You'll get better replies on Perlmonks if you actually ask a question, instead of make a demand. You get especially bad replies if you just copy the text of your homework problem like this.

Must execute in reasonable time, answer does not need to be probably correct.

Oh good, because you cannot have both reasonable (i.e, polynomial) execution time and an exactly optimal answer to the problem you defined.¹ This is exactly the NP-complete bin-packing problem. If you Super Search around this site you can find more information about it (I've already given you a juicy keyword to search for). I know of at least 2 modules out there that could help you to solve this problem.

1: unless P=NP