Net Score Promoter
About
Net Promoter or Net Promoter Score (NPS) is a management tool that can be used to gauge the loyalty of a firm's customer relationships. It serves as an alternative to traditional customer satisfaction research and claims to be correlated with revenue growth.
You can read more about it on wikipedia
How to use
ruby main.rb [1,2,2,4,5,5,7,9,9,10]