recursion

问题 So, I saw someone using the reduce method to calculate the Fibonacci sequence. Here is his idea: (1,0) , (1,1) , (2,1) , (3,2) , (5,3) corresponds to 1, 1, 2, 3, 5, 8, 13, 21 ....... and the code looks like this def fib_reduce(n): initial =(1,0) dummy = range(n) fib_n = reduce(lambda prev ,b : (prev[0] + prev[1], prev[0]), dummy, initial) return fib_n[0] I understand the (prev[0] + prev[1] , prev[0]) which is like a, b = b, b + a . However, I don't understand what this b stands for ? May

问题 I have been practicing the linked list and wanted to implement the recurse on it, although in some cases I was able to implement it efficiently, in other cases I failed miserably at doing so. I would like to know a method to do the recursive so as not to have to use the "while" to go through the Linked List, I have used the recurse to go through the arrays but when I wanted to do it similar in this case it fails. I don't have much experience in implementing recursion and wanted to apply it in

问题 I've got an array of objects. Some of them have a wordpress_parent prop with a value `. This means this node is a child of another node. The actual end result is a nested comment UI, so there can be multiple levels of children. I'd like to loop through my objects and where wordpress_parent !== 0 , find the object in the original array whose wordpress_id equals the value of wordpress_parent and put that object as a child property of the matching parent node. I want to achieve this object form:

问题 I've got an array of objects. Some of them have a wordpress_parent prop with a value `. This means this node is a child of another node. The actual end result is a nested comment UI, so there can be multiple levels of children. I'd like to loop through my objects and where wordpress_parent !== 0 , find the object in the original array whose wordpress_id equals the value of wordpress_parent and put that object as a child property of the matching parent node. I want to achieve this object form:

问题 I am studying my second semester in computer science, in my data structures class we are seeing binary trees with recursion. We have to make the preorder postorder and inorder traversal with recursion based on the following Java code: public class BinaryTree { Node root; public void addNode(int key, String name) { // Create a new Node and initialize it Node newNode = new Node(key, name); // If there is no root this becomes root if (root == null) { root = newNode; } else { // Set root as the

问题 In the post find all combinations with non-overlapped regions (code pasted below), the function is given a set of tuples and it recursively finds every possible collection of tuples with non-overlapping values. On the list of tuples T = [(0.0, 2.0), (0.0, 4.0), (2.5, 4.5), (2.0, 5.75), (2.0, 4.0), (6.0, 7.25)] , for example, we get def nonovl(l, idx, right, ll): if idx == len(l): if ll: print(ll) return next = idx + 1 while next < len(l) and right >= l[next][0]: next += 1 nonovl(l, next,

问题 This question is unlikely to help any future visitors; it is only relevant to a small geographic area, a specific moment in time, or an extraordinarily narrow situation that is not generally applicable to the worldwide audience of the internet. For help making this question more broadly applicable, visit the help center. Closed 8 years ago . I am working on a project. I found this code regarding permutations on the Interwebz. I would like to use it as a basis for writing my own code. However,

问题 ((fn foo [x] (when (> x 0) (conj (foo (dec x)) x))) 5) For this code, the result is [5 4 3 2 1] Why isn't is [1,2,3,4,5]? I see we do conf from result of recursive foo call with a value. For I thought it should be 1 2 3 4 5? Need help to understand this. Thanks. 回答1: From the documentation of conj : clojure.core/conj ([coll x] [coll x & xs]) conj[oin]. Returns a new collection with the xs 'added'. (conj nil item) returns (item). The 'addition' may happen at different 'places' depending on the

问题 friends. I'm trying to write code that hashes all values in a JSON file, regardless of file structure, while preserving the keys and structure. I'm new to javascript, and am having some trouble. My code hashes the values of big and baz, but doesn't recursively hash the values of cat and bar like I want it to. Ideally, I want the numbers hashed and the names (big, foo, etc.) left alone. Thank you so much! See my code below: var meow = { big: 20, baz: { foo: { cat: 3, bar: 5 } } }; console.log

问题 I'm new to Powershell and I've tried finding a solution to my problem online but I can't seem to find one. Basically I need to write something that will let powershell look through all drives and directories to find the following: total number of files (exclude folders), largest file size, average file size, total file size Here's what I've written so far: $source = "get-psdrive" #attempt at looking through all drives/directories which didn't work foreach($a in $source) { #counts files in