recursion

问题 This question already has answers here : Merge two lists (5 answers) Closed 3 years ago . I am looking to write a recursive function to merge to integer lists in F# I started with this, but not sure what to do next. let rec merge xs ys = match xs with | [] -> ys | let li = [1;3;5;7;] let ll = [2;4;5;8;] 回答1: As I said in my comment, it's probably easiest if you pattern match on xs and ys simultaneously: let rec merge xs ys = match xs,ys with | [],l | l,[] -> l | x::xs', y::ys' -> if x < y

问题 I have to search through word index tables with potentially hundreds of thousands rows. I can restrict my search by passing a list of documents to the search. Request to search for words in many documents return very slowly. So...to improve the UX we're chunking the request into several groups of documents. So, if a user asks to search 90 documents, and the chunk size is 10 documents per query, then we send out 90 / 10 = 9 independent $.ajax() calls. We want the results to come in the order

问题 My goal is to display a family tree starting from Person X and showing all descendants. No need to show siblings, parents, or other ancestors. To this end I have a person class. I also have a database table with person_ID and parent_ID columns. When the person class is created you pass it the desired person ID, then it will preload its parents and children IDs from that table. In order to create the descendents tree I wrote the following method inside the person class: public function

问题 need to write a recurive function to remove elements of list but keep the arrays in the result such as. def remove_words(listx): for element in listx: if isinstance(element, list): remove_words(element) else: listx.remove(element) return listx remove_words(["a", "b", ["c"]]) would return [[]] My code returns ["b",[]] for some reason it's missing an element. 回答1: Do not remove elements from a collection while iterating it. Repeated calls to list.remove are also not ideal performance-wise since

问题 My assignment is to solve the Towers of Hanoi for any number using recursion. I wrote my code in C++. Rules: Cannot stack a larger disk on top of a smaller disk. Cannot move more than one disk at a time. ** 3. Only move a disk one peg at a time without going back to the start or going out of the end. <- This is what i'm currently struggling with. ** Following: START --> peg1 <--> peg2 <--> peg3 --> END #include <iostream> #include <time.h> using namespace std; void move(int, int, int, int,

问题 This code should utilize mouse motion events to draw a dot at the current mouse position: import turtle def motion(event): x, y = event.x, event.y turtle.goto(x-300, 300-y) turtle.dot(5, "red") turtle.pu() turtle.setup(600, 600) turtle.hideturtle() canvas = turtle.getcanvas() canvas.bind("<Motion>", motion) The code works as expected for a few seconds or longer if the mouse is moved very slowly. Then it throws: >>> ====================== RESTART: C:/code/turtle_move.py ======================

问题 I'm currently trying to recursively loop through a tree structure and serialize it to a string using (the language) C. I'm a real novice when it comes to C (Coming from a Java, C#, action-script background) and I'm having trouble getting to grips with things in general. Should I use a library to help generate the XML? How do I implement recursion using C? Thanks 回答1: Should I use a library to help generate the XML? Yes. libxml, minixml and others. Just google to know others, but I'd go with

问题 I have created a recursive template for getting the first n number of items from my XML. It uses an index(counter) just like how I would in a for loop. Now how can I get a node from my XML using the index? I have tried [position()=$index] but it had weird behaviour when trying to get deeper nodes in the XML hierarchy. If I have XML such as: <0> <1> <2>item</2> <2>item</2> <2>item</2> <2>item</2> <2>item</2> <2>item</2> </1> </0> I want to be able to count through and copy the 2's until I have

问题 I know I can use expand.grid for this, but I am trying to learn actual programming. My goal is to take what I have below and use a recursion to get all 2^n binary sequences of length n. I can do this for n = 1, but I don't understand how I would use the same function in a recursive way to get the answer for higher dimensions. Here is for n = 1: binseq <- function(n){ binmat <- matrix(nrow = 2^n, ncol = n) r <- 0 #row counter for (i in 0:1) { r <- r + 1 binmat[r,] <- i } return(binmat) } I

问题 I am having trouble writing a method with finding if a MaxHeapPriorityQueue contains a value. The instructions read: The contains(E) method should return true if the given value is found in the queue. It should use its private helper method to search the queue recursively. Here is what I have so far public class MaxHeapPriorityQueue<E extends Comparable<E>> { private E[] elementData; private int size; @SuppressWarnings("unchecked") public MaxHeapPriorityQueue() { elementData = (E[]) new