ASRagab Here's a Scala implementation
arr.flatMap(List.fill(num)(_))
christopher_lil1 Similar to Haskell: concatMap (\num -> replicate n num) arr
MichaelQQ also works: concatMap (replicate n) arr
josemanzoli I think this way is much more readable, even for people that are used to see functional programming codes!
arr.flatMap(e => List.fill(num)(e))
byron_lema Just need to sort the list by adding .sorted
baldockja Could someone explain why we have to pass the parameters as "(a)(b)" instead of "(a, b)".
If this is because "List.fill(a)" returns a function which is then passed "b", then why in the documentation is this code fragment refered to as if it is function in and of itself (http://www.scala-lang.org/api/current/scala/collection/generic/SeqFactory.html#fillA(elem:=>A):CC[A])?
Thanks.
_s_batra Haskell:-
f n arr = do [num | num <- arr , a <- [1..n]]
dillonheins Hi there. Could you possibly explain what is happening here? Is
a <- [1..n]a predicate or just a normal list? What I do understand is that num is the output, you are mapping arr to num but then how does mapping[1..n]toaaffect the output?jonathandygert When you do list comprehensions in Haskell and draw from multiple lists (by doing
x <- list), then the result is a list doing the thing in front for all posible combinations from the lists. Here's an example:[(a, b) | a <- [1, 2, 3], b <- [4, 5]]
gives you
[(1, 4), (1, 5), (2, 4), (2, 5), (3, 4), (3, 5)]
In _s_batra's example, the
ais kinda unused (which also means that by convention it should be named_), but it simply repeats thenumfor each element in[1..n](akantimes).rebornwwp Cartesian product
eliaszx that is also analogous to nested loops in imperative languages(C#, Java) something like:
foreach(var num in arr) { for(var a=1; a <=n; a++) { yield return num; } }
fairjm If you use
fsharp.Code followed is for input.let s = Console.ReadLine() |> int let list = [ let mutable key = Console.ReadLine() while not (key = null) do yield key key <- Console.ReadLine() ]mwojtkowski Thanks !!!
stt106 Nice!!!
edward_trenchar1 spot on - thanks!
lizzael_v_c Thanks!
borsh Thanks a lot!
FlavioFernandes4 Another scala impl:
for{e <- arr; _ <- 1 to num} yield e
DearVolt I'm just learning Scala and this is beautiful :')
wamaral Haskell is so good for these kind of problems
f = concatMap . replicate
ocramius The exercise is wrong/mis-specified.
Mentions "The relative positions of the values should be the same as the original list provided in the input.", but the test cases seem to expect a sorted list.
Discovered it by accident by looking at existing solutions after implementing my own (working against all my own test scenarios) :-(
reggaeguitar This should definitely be specified in the problem description, I'm really glad I read this comment before tearing my hair out.
VardiN I am new to functional programming, But still wanted to try these problems. Can some one tell me what is the logic To break the read cycle in RACKET
I mean in sample test case, after taking 4 how should I break it
abhiranjan Check this :)
(define (read-list) (let ([x (read)]) (if (eof-object? x) (list) (cons x (read-list)))))VardiN thanks :)
kah5368 I've spent countless hours trying to figure this out... thanks a million!
harit66 How did you add code so neatly? mine is screwed up
abhiranjan We follow markdown format. Indenting the code segment by 4 whitespaces (1 tabspace) will work.
zengmor Thank you!
shukla_at Thank you! Had the same problem.
giaym im amazed i managed to compelte it %("$&( odd languages
c_song Struggled a lot for input handling, here is some reference for those having a hard time with erlang.
input(L) -> case io:fread("", "~d") of {ok, [N]} -> input([N|L]); _ -> lists:reverse(L) end. output(L) -> [io:fwrite("~w~n", [H]) || H<-L].
The actual solution with list comprehension is easy as haskell:
[N || N <- X , _ <- lists:seq(1,S)]
xiang19950505 Haskell version:
f :: Int -> [Int] -> [Int] f n arr = arr >>= replicate n
adrielradicchi Here's Elixir implementation
defmodule Solution do def times(n, element) do if (n > 1) do IO.puts element times(n-1, element) else IO.puts element end end def elements(array) do [_ | rest ] = array Enum.map(rest, fn(x) -> times(List.first(array), x) end) end def main() do IO.read(:stdio, :all) |> String.split |> Enum.map(&String.to_integer(&1)) |> elements end end Solution.main
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