Ninety-Nine Clojure Problems

gistfile1.clj

;; http://aperiodic.net/phil/scala/s-99/

; last
(defn p01 [[x & xs]]
  (if xs (recur xs) x))

(defn p02 [xs]
  (p01 (butlast xs)))

; nth
(defn p03 [n [x & xs]]
  (if (zero? n) x (recur (dec n) xs)))

; count
(defn p04 [[x & xs]]
  (if x (inc (p04 xs)) 0))

; reverse
(defn p05 [[x & xs]]
  (if x (concat (p05 xs) (list x)) (list)))

(defn p06 [xs]
  (= (p05 xs) xs))

; flatten
(defn p07 [[x & xs]]
  (cond (nil? x) (list)
	(coll? x) (concat (p07 x) (p07 xs))
	:else (cons x (p07 xs))))

(defn p08 [[x & xs]]
  (cond (nil? x) (list)
	(= x (first xs)) (p08 xs)
	:else (cons x (p08 xs))))



;; FULLLL STOP

(defn p14 [[x & xs]]
  (if x (cons x (cons x (p14 xs))) (list)))

(defn p15 [n [x & xs]]
  (if x (concat (repeat n x) (p15 n xs)) (list)))

(defn p16 [n xs]
  (mapcat butlast (partition n xs)))

; split-at
(defn p17 [n xs]
  (list (take n xs) (drop n xs)))

 

(defn p20 [n [x & xs]]
  (cond (nil? x) (list)
	(zero? n) (p20 (dec n) xs)
	:else (cons x (p20 (dec n) xs))))

(defn p21 [e n [x & xs]]
  (cond (nil? x) (list)
	(zero? n) (cons e (cons x (p21 e (dec n) xs)))
	:else (cons x (p21 e (dec n) xs))))

; range
(defn p22 [from to]
  (if (= from to) (list to)
      (cons from (p22 (inc from) to))))