[Clojure] 4Clojure Easy 3

#30 Compress a Sequence

(fn f [v]

(map first (partition-by identity v) )

)

 

#31 Pack a Sequence

(fn f [v]

(partition-by identity v)

)

;;머지 파티션-바이 를 쓰는게 아닌가..

 

#33 Replicate a Sequence

(fn f [vec repeat_number]

(mapcat #(repeat repeat_number %) vec)

)

#34 Implement range

(defn f [s e]

(take (- e s)

( (fn my-number-seq [s]

(lazy-seq (cons s (my-number-seq (inc s)) ))

) s )))

 

 

#39 Interleave Two Seqs

(fn f [vec1 vec2]
  (mapcat list vec1 vec2)
)

 

#40 Interpose a Seq

(fn f [i vec2]
  (pop (vec (mapcat list vec2 (repeat i)) ) )
)

 

#41 Drop Every Nth item

(fn f [v n]
  (keep-indexed #(if (not= 0 (mod (inc %1) n)) %2) v )
)

 

#42 Factorial Fun

 

(fn f [n]

( (fn fac [c n v]

(if (= c n) v

(recur (inc c) n (* v c)))

) 1 (inc n) 1

)

)

;;재귀적

(fn f [n]

(apply * (range 1 (inc n)) )

)

;;스트림 사용

;;왜 갑자기 펙토리얼?

 

#28 flatten a sequence //못풀었던거

(fn [x] (filter (complement coll?) (tree-seq coll? seq x) ))