gistfile1.txt

(test/with-test
  (defn- swap-duel-probabilities
    ([probabilities]
       {:lead (:follow probabilities) :follow (:lead probabilities)}))
    (test/is (= (swap-duel-probabilities {:lead 0.5 :follow 0.6}) {:lead 0.6 :follow 0.5})))

(defn aggregate-probability
  ([probabilities duelist]
     (reduce
      (fn [sum probability]
        (+ sum (duelist probability))) 0 probabilities)))

(defn perform-duel
  ([lead follow number_of_rounds] (perform-duel lead follow number_of_rounds 1))
  ([lead follow number_of_rounds remaining_chance]
     (cond (= (:w follow) 0) {:lead remaining_chance :follow 0}
                (= (:w lead) 0) {:lead 0 :follow remaining_chance}
                (or (= number_of_rounds 0) (= remaining_chance 0)) {:lead 0 :follow 0}
                :else (let [eventual_kill_probabilities (map (fn [target_wounds]
                                                                 (swap-duel-probabilities (perform-duel
                                                                                           (assoc follow :w (- (:w follow) target_wounds)
                                                                                                  lead)
                                                                                           (- number_of_rounds 1)
                                                                                           (* remaining_chance (to-score-exact-wounds lead follow target_wounds)))
                                                                                          )) (range 0 (:w follow)))
                            immediate_kill_probability (* (to-kill lead follow) remaining_chance)]
                        {:lead (+ immediate_kill_probability (aggregate-probability eventual_kill_probabilities :lead))
                         :follow (aggregate-probability eventual_kill_probabilities :follow)}))))