recursion

问题 I saw three different ways to write the recursive form of a Fibonacci function: With the math inline, With the math inline with result caching and one Using tail recursion with. I understand using memoization converts an O(N) algorithm to an O(1) after the answers are cached. But I fail to understand how tail call optimization can help this much. I was under the impression it might prevent a few copies or something like that. It is nearly as fast as the O(1). What is Ruby doing that makes

问题 def index(L,v) ''' Return index of value v in L ''' pass I need help with implementing this function using recursion. Really new to recursion stuff so any advice would help! Note that L is a list. v is a value. 回答1: That works def recursive_index(L, v): return 0 if L[0] == v else 1 + recursive_index(L[1:], v) but is pretty stupid (and will only work if the value exists) You can add if v not in L: return -1 to make it work for any case, but that is even worst. Do it really has to be recursive?

问题 def index(L,v) ''' Return index of value v in L ''' pass I need help with implementing this function using recursion. Really new to recursion stuff so any advice would help! Note that L is a list. v is a value. 回答1: That works def recursive_index(L, v): return 0 if L[0] == v else 1 + recursive_index(L[1:], v) but is pretty stupid (and will only work if the value exists) You can add if v not in L: return -1 to make it work for any case, but that is even worst. Do it really has to be recursive?

问题 This question already has answers here : Closed 7 years ago . Possible Duplicate: Linked list recursive reverse I searched my question on SO and got a link recursion stack trace I din't understand How the head_ref is Pointing to 4 there? Could anyone help me to understand this? 回答1: ok, first of all, it's 6 am here, and i couldn't sleep all night ... so this might be bullshit ;) ... but here we go: the "magic" happens at recursiveReverse(&rest); ... the & says that the parameter is the

问题 Okay everybody, I know the knight's tour problem is popular for all cs students and I am having trouble getting mine to work. I use this recursive algorithm to progress through the moves, however, once I get to around move 50 I have to backtrack since no moves are available and I end up never completing the tour. I pass a ChessNode (holds things like if node has been visited, move it was visited, etc...), next row, next column, and previous node's move count. private int moveRecur(ChessNode

问题 I have a set of companies in rank order. I want my rule to check if the companies in a specified list are in rank order, and for the rule to recur until all companies in the list have been checked. I currently have the following: isOrder([]). isOrder([COM1,COM2|T]) :- rank(COM1,D), rank(COM2,E), D<E, print("in order"), isOrder([COM2|T]). However, this does not seem to work. Sometimes, the recursion goes on forever without ending, and sometimes the recursion doesn't work at all. This is when I

问题 I have a list of over 10000 items and using recursion i want to iterate over all the possible combinations of their selection starting from 1st item for both its selection and not selection ( 2 branches ) then deciding on 2nd item for each branch and so on till last item in DFS way. I am using this code for optimization and most of the branches are not iterated over but atleast 1 leaf will be reached as to find the best the problem is I made a recursion code in python and it works fine for

问题 I'm not quite understanding recursions. I'm working on a class program, and I converted most of my program to recursions. So, my professor doesn't want us to use loops and also doesn't want us to use more than one parameter. The program runs through the hailstone sequence and the function I'm having trouble computes the length of the hailstone sequence. I had it working my way, but wanted to confirm if it was up to his standards. (Is not to his standards.) I wanted to know if there was a

问题 This question already has answers here : What are the boundaries of recursion? (2 answers) Closed 3 years ago . Given let doAsynchronousStuff = () => { return new Promise(resolve => { setTimeout(() => { resolve("abcdefg"[Math.floor(Math.random() * 7)]) }, Math.PI * 1 + Math.random()) }) .then(data => console.log(data)) .then(doAsynchronousStuff) } why is .then(doAsynchronousStuff) considered "pseudo-recursion"? What is the difference between "recursion" and "pseudo-recursion"? Context: this

问题 I am trying to break a javascript object in to small array so that I can easily access the innerlevel data whenever I needed. I have used recursive function to access all nodes inside json, using the program http://jsfiddle.net/SvMUN/1/ What I am trying to do here is that I want to store these in to a separate array so that I cn access it like newArray.Microsoft= MSFT, Microsoft; newArray.Intel Corp=(INTC, Fortune 500); newArray.Japan=Japan newArray.Bernanke=Bernanke; Depth of each array are