The problems are usually relatively simple and can be reviewed as a group every 20 minutes or so. Recently at MakersAcademy we've had great fun with CodeWarsJams, where we take coding kata from http://codewars.com and use them to run a codejam. CodeWars is great because when you solve a problem you get to see all the other variant solutions that others have coded, sorted by popularity. Come join the festive coding fun as LRUG's first CodeWarsJam!