Write some Software

I want to build a "invite score" software write on Scala and using concepts of funcional programming where: - The inviter gets (1/2)^x for each confirmed invitation where x is the level of the invitation: evel 0 (people directly invited) yields 1 point, level 1 (people invited by someone invited by the original customer) gives 1/2 points, level 2 invitations (people invited by someone on level 1) awards 1/4 points and so on. - If a person receive multiple invites, only the first one will count. - To count a valid invitation, invited person must have invited someone; Ex.: So, given the input: 1 2 1 3 3 4 2 4 4 5 4 6 The score is: 1 - 2.5 (2 because he invited 2 and 3 plus 0.5 as 3 invited 4) 3 - 1 (1 as 3 invited 4 and 4 invited someone) 2 - 0 (even as 2 invited 4, it doesn't count as 4 was invited before by 3) 4 - 0 (invited 5 and 6, but 5 and 6 didn't invite anyone) 5 - 0 (no further invites) 6 - 0 (no further invites) The program input will be a text file where each person identifier will follow the format "INVITER\tINVITED".