Clojure LeetCode Online Judge: Find Peak Elements

(defun num-peak (lst &optional (n 1) (r nil))
  (cond ((null (cddr lst)) r)
        ((and (> (cadr lst) (car lst)) (> (cadr lst) (caddr lst))) (num-peak (cdr lst) (+ n 1) (cons n r)))
        (t (num-peak (cdr lst) (+ n 1) r))))
 
==> num-peak
 
(num-peak '(1 12 3 14 5 6))
 
==> (3 1)

(defun peak-numbers (w &optional (n 1))
  (cond ((null (cddr w)) nil)
        ((and (> (cadr w) (car w))
              (> (cadr w) (caddr w)))
         (cons n (peak-numbers (cdr w) (1+ n))))
        ((peak-numbers (cdr w) (1+ n)))))
 
> (peak-numbers '(0 1 0 1 2 3 1))
(1 5)

(defun peak-numbers (w &optional (n 1) &aux (d (cdr w)))
  (cond ((null (cdr d)) nil)
        ((and (> (car d) (car w))
              (> (car d) (cadr d)))
         (cons n (peak-numbers d (1+ n))))
        ((peak-numbers d (1+ n)))))
 
> (peak-numbers '(0 1 0 1 2 3 1))
(1 5)

(num-peak '(5 4 3 2 1 2 3 4 5))
==> nil

(< a b c)
(> a b c)

(defun peak-i (w &optional (n 1) &aux (d (cdr w)))
  (cond ((null (cdr d)) nil)
        ((> (cadr w) (max (car w) (caddr w)))
         (cons n (peak-i d (1+ n))))
        ((peak-i d (1+ n)))))

;; racket-lang.org
(define (peak-values lst)
  (for/list ((left (cons (sub1 (car lst)) lst))
             (center lst)
             (right (cdr lst))
             #:when (> center (max left right)))
    center))
 
(define (peak-indexes lst (v (list->vector lst)) (v-r vector-ref))
  (for/list ((indexes (in-range 1 (sub1 (length lst))))
             #:when (> (v-r v indexes)
                       (max (v-r v (sub1 indexes))
                            (v-r v (add1 indexes)))))
      indexes))
 
(peak-values '(1 12 3 14 5 6))
;'(12 14)
(peak-indexes '(1 12 3 14 5 6))
;'(1 3)

(ns aeon.core)
 
(defn task [coll]
  (->> (partition 3 1 coll)
       (keep-indexed (fn [idx [st nd rd]]
                       (when (and (> nd st) (> nd rd))
                         (inc idx))))))
;; => #'aeon.core/task
 
(task '(1 12 3 14 5 6))
;; => (1 3)
(task '(0 1 0 1 2 3 1))
;; => (1 5)