recursion

问题 Suppose we have some Foo object that allows: cout << myFoo[3]; myFoo[5] = "bar"; This calls for a proxy design-pattern (detailed by Scott Meyers here) But now let us suppose every myFoo[i] is also a Foo instance. myFoo[7] = Foo{...}; myFoo[5] = "bar"; // Foo has a Foo(std::string) non-explicit constructor I'm close to having an implementation, but I can't get rid of one final pesky "forward declaration/ incomplete type" error. Firstly, let's get the easy one out of the way: // x =

问题 I'm still new to C++ and as of right now learning recursion. I wanted to display the elements in reversed order without starting the index of the array at the end using recursion. Obviously it would be very easy to do using loops, but using recursion is a different matter. I found this solution to the problem online, but can't understand how exactly its able to print out each value. void recArrayBackPrint(int array[],int size) { if (size > 0) { recArrayBackPrint(array+1,size-1); cout << array

问题 I have little experience in any higher level language. Fiddled with basic and dos-batch when I was a kid. I'm trying to find the point value of a word in scrabble. This kind of recursive structure seems slow and inefficient. What would be a better way to address this problem in terms of program structure/concept? value_list = {'a': 1, 'b': 3, 'c': 3, 'd': 2, 'e': 1, 'f': 4, 'g': 2, 'h': 4, 'i': 1, 'j': 8, 'k': 5, 'l': 1, 'm': 3, 'n': 1, 'o': 1, 'p': 3, 'q': 10, 'r': 1, 's': 1, 't': 1, 'u': 1,

问题 I am new to JavaScript and am trying to understand an example from the book. When I step through this example, I expect the value of fac(4) to be 12. That would be the result of (4 - 1) * 4. However, when I run the code from the online book (near bottom of page) at http://eloquentjavascript.net/00_intro.html, I get the value 24. What am I missing here? function fac(n) { if (n == 0) return 1; else return fac(n - 1) * n; } console.log(fac(4)); I have tried to find an answer through Twitter and

问题 I'm trying to make a rock-paper-scissors game, and am trying to verify the input. def player1(): x = (raw_input("please select: Rock(r)/Paper(p)/Scissors(s): ")).lower() if x == 'r' or x == 'p' or x == 's' or x == 'rock' or x == 'paper' or x == 'scissors': return x[0] else: print "Error - wrong input!" player1() #I know I can run a While loop, but I need to run it this way. print(player1()) If I enter the right input on the first try, everything works fine. But if I enter wrong input on first

问题 I have a little problem with a recursion in php. I have read many articles but the solution doesn't come. I have this array: [59] => Array ( [ID] => REL000000 [Name] => RELIGIONE / Generale [Description] => [IdParent] => ) [799] => Array ( [ID] => REL102000 [Name] => RELIGIONE / Teologia [Description] => [IdParent] => REL000000 ) [800] => Array ( [ID] => REL068000 [Name] => RELIGIONE / Teosofia [Description] => [IdParent] => REL000000 ) [801] => Array ( [ID] => REL103000 [Name] => RELIGIONE /

问题 I'm attempting to learn about dynamic programming and recursion for Python 3.x. The code below is a simple example from my textbook: def recMC(coinValueList, change): minCoins = change if change in coinValueList: return 1 else: for i in [c for c in coinValueList if c <= change]: numCoins = 1 + recMC(coinValueList, change-i) if numCoins < minCoins: minCoins = numCoins return minCoins print(recMC([1,5,10,25], 63)) I'm really struggling to understand line 6 here, the line comprehension. I'm

问题 Go easy on me, this is my first question ;) I've spent a lot of time looking, but I haven't found what I'm looking for. I've got an intranet based reporting tool (VB.Net + ASP.Net Integrated Windows Authentication) that looks up users and managers from a SQL Server 2005 table to roll up the reporting to manager level. This table is currently manually maintained and I've been asked to make it more dynamic as it is going to be up-scaled for far more users. Therefore I'm looking to link in with

问题 I want to write a function in Racket which takes an amount of money and a list of specific bill-values, and then returns a list with the amount of bills used of every type to make the given amount in total. For example (calc 415 (list 100 10 5 2 1)) should return '(4 1 1 0 0) . I tried it this way but this doesn't work :/ I think I haven't fully understood what you can / can't do with set! in Racket, to be honest. (define (calc n xs) (cond ((null? xs) (list)) ((not (pair? xs)) (define y n)

问题 This question regarding exercise 5.5 from Think Python 2 has been asked and answered already, but I still don't understand how this function works. Here's the function in question: def draw(t, length, n): if n == 0: return angle = 50 t.fd(length*n) t.lt(angle) draw(t, length, n-1) t.rt(2*angle) draw(t, length, n-1) t.lt(angle) t.bk(length*n) I see a recursive loop here: def draw(t, length, n): if n == 0: return angle = 50 t.fd(length*n) t.lt(angle) draw(t, length, n-1) After the function