A database query problem for those who are interested:
There is a table with two columns: userId, time (many to many relationship)
For every pair of userIds, if any two time difference of two users is less than 20 minutes, then the pair will get a point.
Now need to find out the pair with highest points.
Then points of pair:
ab = 2
ac = 3
bc = 3
PS: This query may be used for data mining and/or artificial intelligence.
PS: It can also be used for trolling 3:)
PS: Idea courtesy – Nipa Afroz