bird-watcher.clj

(ns bird-watcher)

(def last-week [0 2 5 3 7 8 4])

(defn today [birds]
  (last birds))

(defn safe-last-index [v]
  (if (empty? v)
    nil ; or some appropriate value
    (dec (count v))))

(defn inc-bird [birds]
  (let [last-idx (safe-last-index birds)
        new-count (inc (today birds))]
    (assoc birds last-idx new-count)))

(defn day-without-birds? [birds]
  (some? (some zero? birds)))

(defn n-days-count [birds n]
  (apply + (take n birds)))

(defn busy-days [birds]
  (count
   (filter #(>= % 5) birds)))

(defn odd-week? [birds]
  (= birds [1 0 1 0 1 0 1]))