4clojure solutions

4clj.clj

;; https://www.4clojure.com/problem/19
(fn [x] (first (reverse x)))


;; https://www.4clojure.com/problem/20
(fn [x] (second (reverse x)))

(fn [x] (first (rest (reverse x))))


;; https://www.4clojure.com/problem/21
(fn nth-element [c, n] (second (take-nth n s)))

(fn nth-element [c n] (if (zero? n) (first coll) 
            (nth-element (rest coll) (- n 1))))

(fn [c n] (if (zero? n) (first c) 
            (recur (rest c) (- n 1))))

(fn [c n] (if (zero? n) (first c) 
            (recur (rest c) (dec 1))))

(fn [c n] ((apply comp (cons first (repeat n rest))) s))


;; https://www.4clojure.com/problem/22
(fn [c] (reduce (fn [n e] (inc n)) 0 c))

(fn [c] (reduce + (map (fn [x] 1) c)))


;; https://www.4clojure.com/problem/23
(fn [c] (reduce (fn [a i] (cons i a)) '() c))


;; https://www.4clojure.com/problem/24
(fn [c] (reduce + c))


;; https://www.4clojure.com/problem/25
(fn [x] (take x ((fn fib [a b] (cons a (lazy-seq (fib b (+ a b))))) 1 1)))