rendezvous with cassidoo challenge: 22.10.17

pass_doors.clj

(ns pass-doors
  (:require [clojure.test :refer [deftest is]))

(defn pass-doors [n number-of-passes]                                                            
  (let [initial (repeat n 1)                                                                     
        passes  (range number-of-passes)                                                         
        toggle-door     (fn [d] (if (zero? d) 1 0))                                                 
        create-sections (fn [doors pass]                                                          
                          (map vec (partition-all (inc pass) doors)))                             
        toggle-section  (fn [section pass]                                                        
                          (if (< pass (count section))                                            
                            (assoc section pass (toggle-door (last section)))                     
                            section))                                                             
        run-passes (reduce (fn [doors pass]                                                      
                             (mapcat #(toggle-section % pass) (create-sections doors pass)))      
                           initial                                                               
                           passes)]                                                              
    (count                                                                                       
      (filter zero? run-passes))))                                                               
                                                                                                 
(deftest pass-doors-test                                                                         
  (let [n 7                                                                                      
        number-of-passes 3]                                                                      
    (is (= 4 (pass-doors n number-of-passes)))))