ab.clj

(ns ab)

(defn- bump [f m]
  (into {} (map (juxt (comp f key) val) m)))

(defn- turn [[a b]]
  (mapv #(merge-with + b (bump % a)) [inc dec]))

(->> {0 1N}
  (repeat 2)
  (iterate turn)
  (drop 99)
  first
  (apply merge-with +)
  (group-by #(compare (key %) 0))
  (map (juxt (comp {1 :a -1 :b} key) #(->> % val (map peek) (apply +))))
  (filter first)
  (sort-by first)
  prn)