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I have passed all testcases beside 9 and 10. I'm using substring function, readLine and print, I think for large inputs some of this methods doesn't work properly. Could you help me?
For each addition operation, a new memroy block of N+M size is allocated. Probably due to this, you are running short of memory, leading to memory limit exceeded.
Thanks. It will be great if you could mention the above detail in Editorial Section also. I had solved the problem using different approach. I would have missed this information if I had not read discussion board.
Scala does tail recursion optimisation at compile-time and the recursive function is transformed into a loop by the compiler
I was wondering why the following solution says "Run Time Error"
I have modified this code several times but I always get TLE for las test case. I don't know why, when I use List[Char], to my mind when I use ch :: list this executes in O(list.length) time and can I do this adding in constant time or how can I make my code faster?
you mean list :: ch ?
When I wrote list :: ch1 :: ch2 I didn't compile then I thought It's wrong in scala. I don't have much experience in scala, It's almost a week I code in it
many compilers are optimized for tail-recursion which makes such functions less inefficient than one would normally expect them to be. For example, the tailRec keyword in Scala.
This is the solution that I eventually came up with and it still times out on test case 10. Interestingly, a simple for loop which prints out the characters of the strings also times out on that case and is about twice as long in execution on test case 9.
On my local machine, I get stack overflow way before the execution time problem.
Any suggestions?
Common source of long execution is the complexity of + operator (or append method) for strings. It's of Appending two strings, one of length N, other of M, is of complexity O(N+M). Here it's repeatitive addition, so it can be of quadratic complexity.
Sorry, I meant the onbe that you posted. Here is my version:
def Mingle(P:List[Char],Q:List[Char]):List[Char] = {
if(P.isEmpty)return List()
return P.head :: Q.head :: Mingle(P.tail,Q.tail)
}
def main(args: Array[String]) {
val P = readLine().toList
val Q = readLine().toList
println(Mingle(P,Q).mkString)
}
String Mingling
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I have passed all testcases beside 9 and 10. I'm using substring function, readLine and print, I think for large inputs some of this methods doesn't work properly. Could you help me?
Hi @bolean, in java/scala, the complexity of
s1.concat(s2)ors1 + s2is O(M + N) where M and N are the respective String lengths, instead of O(1).Oh, thanks I didn't know that, but still I got runtime error for those test cases and can that be caused by this reason?
For each addition operation, a new memroy block of N+M size is allocated. Probably due to this, you are running short of memory, leading to memory limit exceeded.
Mmm, I think I guess the point. I'm starting to like scala more. ^_^
Thanks. It will be great if you could mention the above detail in Editorial Section also. I had solved the problem using different approach. I would have missed this information if I had not read discussion board.
Scala does tail recursion optimisation at compile-time and the recursive function is transformed into a loop by the compiler I was wondering why the following solution says "Run Time Error"
}
Is it because of same reason ?
use StringBuilder for concat operation in scala
code is working fine in my terminal. I feel you missed to import. import scala.annotation.tailrec
I have modified this code several times but I always get TLE for las test case. I don't know why, when I use List[Char], to my mind when I use ch :: list this executes in O(list.length) time and can I do this adding in constant time or how can I make my code faster?
Did you try it in reverse order :)
you mean list :: ch ? When I wrote list :: ch1 :: ch2 I didn't compile then I thought It's wrong in scala. I don't have much experience in scala, It's almost a week I code in it
Something like
PS: Almost all the challenges are designed such that you don't need mutable variables to solve them.
Thank you it finally accepted. I'll check for differences those codes to understand what was the problem. Thank you again
Hello! I wonder why is this solution is better than mine:
It is tail recursive function, list concatenation has linear complexity
many compilers are optimized for tail-recursion which makes such functions less inefficient than one would normally expect them to be. For example, the tailRec keyword in Scala.
@serhii_nesteruk,
::has constant complexity, while++is linear.In your code you are applying
++n times. First on the list of length 1, then 2, then 3, and so on. So overall complexity will bethanks for the explanation!
This is the solution that I eventually came up with and it still times out on test case 10. Interestingly, a simple for loop which prints out the characters of the strings also times out on that case and is about twice as long in execution on test case 9. On my local machine, I get stack overflow way before the execution time problem. Any suggestions?
Hi @blowkj, sorry can't find your solution.
Common source of long execution is the complexity of
+operator (or append method) for strings. It's of Appending two strings, one of length N, other of M, is of complexityO(N+M). Here it's repeatitive addition, so it can be of quadratic complexity.Sorry, I meant the onbe that you posted. Here is my version: def Mingle(P:List[Char],Q:List[Char]):List[Char] = { if(P.isEmpty)return List() return P.head :: Q.head :: Mingle(P.tail,Q.tail) }
Note that I don't use the + operator. Thanks,
OK, got it now. Googling on tail recursion helped.
Hi @abhiranjan
I have the same issue (using F sharp).
However, the last two cases timed-out. On a standard laptop they work just fine.
Hi, sorry I missed this one. You can access other F# accepted solutions at leaderboard. Please feel free to refer them.