game.clj

(defn longest-equal-subseq-for
  "Returns the longest subsequence of indices for which the following
  statement is true:
  for all i, j in subsequence: (f i) = (f j) != nil
  If there are subsequences of equal size, the last one is returned."
  [f indices]
  (let [subseqs (remove (comp nil? first) (partition-by f indices))]
    (if (seq subseqs)
      (apply (partial max-key count) subseqs)
      subseqs)))