This is an algorithm to detect some specific cases for fraud prevention I submitted in codesprint 2. The challenge is Fraud prevention submitted by Groupon, and I managed to pass only 3 test cases out of 5 Codesprint 2: http://cs2.interviewstreet.com Fraud prevention challenge: http://cs2.interviewstreet.com/recruit/challenges/solve/view/4f0a70674f380/4f00b1502c006