fpExploring functional programming with a co-workerweek 1: https://www.hackerrank.com/challenges/super-digitweek 2: http://rosettacode.org/wiki/100_doorsweek 3: https://www.hackerrank.com/challenges/messy-mediansweek 4: http://www.ctl.ua.edu/math103/euler/ifagraph.htm