Let’s assume that you have a sales order like the one below:
Create a decision model that is capable of deciding which product lines inside such orders are duplicated. The duplicate product lines can be recognized by user-defined similarity rules, e.g. two product lines are considered “duplicate” if they have the same “sku” and “price”.
Download attached PDF for solution. This problem is also discussed more fully here https://dmcommunity.wordpress.com/challenge/challenge-august-2015/
You can also find other vendor's solutions on that website (though many won't be able to solve it without resorting to Java)