haskell - How does this memoized fibonacci function work? -

-

In the current practice assignment of functional programming courses, we've got to create a memoized version of one given For the interpretation of the function of memoanization, the following example has been given: 

  fiblist = [fibm x | X & LT; - [0 ..]] FIBM 0 = 0 FIBM 1 = 1 FIBM N = FBL !! (N-1) + Fibliëlt !! (N-2)   
 But I do not fully understand how it works.  
 Let's call  fibm 3 .  
  FILM 3 - & gt; FIBIL !! 2+ FB list 1 - & gt; [Fiber 0, Fimboma 1, FB 2] !! 2 + [Fib 0, FIBM 1] !! 1 - & gt; FIMBUM 2 + FIBM1 - & gt; (Fiberlist !! 1 + Fibliast 0) + 1 - & gt; ([FIBM 0, Fib 1] !! 1 + [FIBM 0] !! 0) + 1 - & gt; (FImM + 1FBM) + 1 - & gt; 1 + 0 + 1 - & gt; 2   
 With other questions / answers and googling, I have learned that in some way, the evaluation is shared between the FB list.  
 Does this mean that, for example,  fiblist !! 2+ FB list !! 1 , the list value is only calculated once for the  fiblist !! 2  and then just reused for  fiblist !! 1 ?  
 Then two Fibonacci numbers are calculated once per call, so there is no unimportant number of calls. But what about the "lower" level of the call in the  Fiberlist  function? In the original  fibm  call         "text"> 
 The important part here is that the list has been evaluated appropriately, which means that the element is not requested for the first time. Once it has been evaluated, there is more to see it. So in your example, you are saying that the value is calculated only once for the  fiblist !! 2  and then reused for  fiblist !! 1 .  
 The 'lower level' of the Fibbles function works the same way. For the first time I call  fiblist !! 1 will be evaluated by calling  fibm 1  which is only 1, and this value will be in the list. When you try to get a high fibonacci number, then call  Fiberlist  to  FILM , which will see those values ​​in less - and potentially already evaluated Done -  fiblist status .

Comments

Post a Comment

Popular posts from this blog

excel vba - How to delete Solver(SOLVER.XLAM) code -

-
After opening several examples of macro / code written, I suddenly get stuck with a code that seems safe. Solver (SOLVER.XLAM) is doing this notation and I would like to remove it from my system. I do not think this is a relativant code. Can anyone tell me what should I do? I have already installed something to remove the password but Solver is still asking for password and I can not get rid of it! itemprop = "text"> Solver Excel is add-in If you want to delete it, then Excel Application & gt; Options & gt; Add-ins & gt; Search for 'Go to' button and gt; Uncheck the solver on the list like press something (I can not give you the exact path because I have the Polish version of Excel). Trying to open Solver's VBA code is not good because it There is allegedly copyright. Besides, I do not think Solver creates any disadvantages while working with Excel or VBA.
Read more

github - Teamcity & Git - PR merge builds - anyway to get HEAD commit hash? -

-
I have a team city build project with Gitbab VCS route, I have been triggered for both / head on PR and / Merge the referee. The annoying thing is that you can not do anything useful with the merged hash - it is not present in Gitobb. I want to exclude newsgate packages with head in gutub comet situations in the version number along with Hewash (Newsaging 7) for the music build, but against head hash. However, I can not see a way to get the head hashes while constructing that merge. I just want to head because it's useless - we only care about merge. (PR - Pull Request) This command works reliably while running One on / merge is git log --no-merge -1 ---- = '% h'
Read more

ios - Replace text in UITextView run slowly -

-
I have a UITextView and I change a word like the code at the end of UITextView.text: - (void) Replace TexttechWitWord: (NSString *) word {NSString * currentTextViewText = self.textView.text; CurrentTextViewText = [currentTextViewText stringByReplacingCharactersInRange: NSMakeRange ([self.textView.text length] - [word length], [word length]) withString: word; Self.textView.text = currentTextViewText; } Replacement work is fine, but it runs very slowly and very slowly when the textView now lengthens Is there any better way? I try the replacement range: with text for a week but still stuck. Not to know how to use it to replace it in your case. Please guide! Thanks in advance! This is an important job. As you are using an irreversible string and you are creating a very long string and before Assigned to NSString created from. NSString will be used instead of NSMutableString . - (UITableViewCell *) TableView: (UITableView *) Table View CellForOutPath: (NSIndex...
Read more