Questions tagged [recursion]

For questions about recursion, the practice of calling a method or function from within itself.

Filter by
Sorted by
Tagged with
-4
votes
0answers
30 views

Proper recursive rendering in React

I'm trying to render a recursive list from a json file. Could you please suggest a proper way to render children (and their children etc.)? Those elements are stored in entry.children By now I can ...
-4
votes
0answers
26 views

Recurrence: Find minimum total stock price

Given a matrix of size N by T, the i-th row and j-th column is the price of buying i shares of a stock at time j. What's the minimum cost of buying in total N shares at the end of time T? So this ...
0
votes
5answers
178 views

How to deail with a hypothetical situation in which a pub/sub cycle gets into an unending recursive loop?

Let me explain what I mean. Imagine A subs to event b. In such case A pubs event a. B subs to event a. In this case B subs b. This is a full-blown circle. How does a pub/sub cycle deal with such ...
-3
votes
2answers
79 views

Recursion + Stack/Queue usage in practical life implementation [closed]

I am very new to Data Structures and Algorithms. I want to use recursion + stack/queue in a grocery store inventory program that I am making. However, I can't come up with any good ways of using ...
0
votes
1answer
67 views

Recursive speculative display list engine - computing text length across stack boundaries

Well, I've been hammering away on this for about a week now with no practical progress because I can't find mental fluidity with the concepts I'm trying to wrangle. I'm Officially Stumped, and would ...
-2
votes
1answer
428 views

Iterative Sorts vs. Recursive Sorts

Naive sorts like Bubble Sort and Insertion Sort are inefficient and hence we use more efficient algorithms such as Quicksort and Merge Sort. But then, these two sorts are recursive in nature, and ...
4
votes
6answers
2k views

Making recursion optional: Bad practice?

Let's say I have a function like this: /* Mode is a bool that determines whether the function uses it's recursive mode or not */ public static int func(int n, boolean mode) { if (!mode) ...
1
vote
2answers
155 views

Representing a recursive Structure in OOP

I want to represent an Edifact message in an OOP Language. An Edifact message has the following structure: message := [ ( segment | segmentgroup ) ] segmentgroup : = [ ( segment | segmentgroup )...
0
votes
1answer
154 views

Walking a graph without recursion

I'm working on a class that receives a relational EDM/data model (e.g. a SQL DB or OData API manifest) and performs a couple tasks on them (not necessarily at the same time, could be two separate runs)...
2
votes
5answers
510 views

If the whole point of recursion is to break the problem into multiple smaller problems, what if those problems were solved in parallel?

So I was studying here and I was thinking if the whole point of recursion is to break the problem into multiple smaller problems, what if those problems were solved in parallel? A quick search lead me ...
-1
votes
1answer
293 views

What happens when loops are compiled or interpreted?

I have came across a concept in recursion which says that when loops are compiled or interpreted then they get converted to recursive functions. If it is true how it takes place ?
2
votes
1answer
1k views

How to optimize reusing a large std::unordered_map as a temporary in a frequently called function?

Simplified question with a working example: I want to reuse a std::unordered_map (let's call it umap) multiple times, similar to the following dummy code (which does not do anything meaningful). How ...
1
vote
2answers
735 views

Pass-Through parameters in recursive code

When writing large amounts of recursive code (for valid reasons), I have come across many parameters that are not used in specific functions, but are still needed for a subset of all of the functions. ...
-1
votes
1answer
502 views

True or false about recursion

I am working on a quiz for a computer science course. I would like to check that the following statement is false: A recursive call may never generate more than one recursive call for the ...
0
votes
1answer
109 views

Express unique recursive task system

I would like to express a task as either itself or a container for other tasks (recursively). The problem is that each task has to be one of two fundamental types: a goal or a routine. And, children ...
2
votes
2answers
1k views

Patterns for tracking state in recursive Haskell code

A frequent pattern in my Haskell code is element-wise recursion for transformation of a list with some carried state generated using the data in the list. Usually, this looks something like this: ...
0
votes
1answer
92 views

Generating combinations without getting stuck in recursive calls

This question is about figuring the design of a recursive function that changes the state of a group of elements by processing one of them at a time, with the goal of reaching a desired state. The ...
6
votes
0answers
154 views

Why does GHC represent recursion in Haskell with recursive binders instead of a fixpoint operator?

GHC's Core data type represents recursion with recursive binders in the Let constructor; as I understand it, all let expressions in Haskell are effectively let rec expressions. Why does GHC use this ...
3
votes
1answer
189 views

What is best practice for handling mapping arbitrary depth in arrays?

I have a set of data: id | name | parentid ------------------------ 1 | parent | 0 2 | child | 1 3 | child | 1 4 | parent | 0 5 | child | 4 6 | subchild | 5 7 | child | 4 ...
0
votes
1answer
49 views

Question about memory handling of trees and certain sorts on large data sets.

If data structures such as trees and certain sorts(quick sort, merge sort) work using recursive algorithms and recursive algorithms take up a lot of memory space in the stack and can only work on a ...
-1
votes
1answer
107 views

Inserting at head for a recursively defined linked list

This article states However, this design does run into problems with some of the methods of the MutableSequence ABC. Most notably, insert and __ delitem __ can't operate on position 0, because ...
0
votes
1answer
1k views

An elegant way to detect the end of an asynchronous recursive file search?

Given a recursive subroutine in single threaded environment which starts numerous asynchronous I/O operations and registers callback functions for each of them. This callbacks will be called on the ...
0
votes
1answer
293 views

Recursion explanation

I am not able to understand this basic recursion example. When I executed this code. The output was 43210. Should not the output be 44444, as the value of num is updated to 4 to the latest recursive ...
0
votes
1answer
147 views

Memoization in case of recursive interdefined functions in Haskell/Functional Programming?

I was reading Memoization with recursion which tells how for a recursively defined function fun we can do memoization by: -- Memoization memoize f = (map f [0 ..] !!) -- Base cases g f 0 = 0 g f 1 = ...
10
votes
4answers
1k views

What are the considerations to determine whether you can use recursion to solve a problem?

Sometimes in interviews, I may use recursion to solve a problem (such as adding 1 to an infinite precision integer), or when the problem presents itself suitable to use recursion. Sometimes, it might ...
0
votes
1answer
1k views

Eliminating recursion

It is easy to eliminate tail recursion. There are few curious cases where the not-tail recursion can also be eliminated. Exhibit 1: Fibonacci numbers. A naive recursive solution fib(n) if (n &...
1
vote
1answer
2k views

How do I represent a recursive process down a tree in a sequence diagramm?

I'm working on a sequence diagram for a layered system that has a tree hierarchy. Now I have a process that works itself recursively down the tree. Meaning calling the same function on a child object. ...
2
votes
2answers
2k views

Efficiency considerations: nested loop vs recursion

I would consider myself an intermediate Python programmer. One of my recent challenges was creating a list of all possible solutions to a given Countdown problem. Without getting into too much detail,...
0
votes
2answers
436 views

How do I write an algorithm to solve a set of 3 symbolic equations

Replace each symbol (letter) with a number so that the equations hold across all 3 equations. Solution should be able to solve the general case of any 3 equations. Can assume 2 terms summed to an ...
0
votes
1answer
77 views

Why isn't this combinatorial solution equivalent to the recursive solution for finding the number of “paths”?

Here's the problem: Given an m x n array, get the number of different paths from the top left corner to the bottom right corner, if you can only move down, right, and diagonally down & right. ...
6
votes
4answers
11k views

Why does recursion return the first call in the stack and not the last?

I cant for the life of me figure out why this returns 0 rather than 5. i keeps getting incremented before it hits the last return statement, however it always returns 0, from the first call in the ...
5
votes
1answer
1k views

How does K&R's qsort work?

In the recursion section of K&R's ANSI C book, they demonstrate a version of quicksort [that] is not the fastest possible, but it's one of the simplest. --The C Programming Language (ANSI ...
0
votes
2answers
515 views

How to decide how to build a recursive function

Sometimes when you're coding you're on a problem which can be solved with some recursive method. What is for you the best way to detect when the recursion is a good way to solve a problem and how to ...
2
votes
2answers
2k views

Designing the recursive solution

I understand the recursion and find it useful and intuitive while solving problems on trees but for many other problems recursion never fails me to leave puzzled. Recently I was solving the following ...
3
votes
1answer
359 views

Are recursions intrinsically less safe than iterations?

Java doesn't have a predefined recursion depth limit. As a result the recursion below (a dummy method that returns the value) throws java.lang.StackOverflowError after 62844 (with static) and 14002 (...
0
votes
1answer
9k views

how is stack and heap are assigned to each processes?

How multiples processes are stored in the main memory , i understand every process will be divided into the equal size pages and will be stored in the frames of main memory. if whole main memory is ...
39
votes
11answers
19k views

Is a while loop intrinsically a recursion?

I wondered whether a while loop is intrinsically a recursion? I think it is because a while loop can be seen as a function that calls itself at the end. If it is not recursion, then what is the ...
3
votes
3answers
1k views

How to mentally keep track of recursion

I have great trouble doing recursion, especially trying to visualize it. A great example is the aging wine problem described in the top answer of this link: https://www.quora.com/Are-there-any-good-...
3
votes
5answers
11k views

Recursion in Merge Sort algorithm. How is it obvious to use this type of recursion?

I dont want to put too much code so I'll just put the code that involves recursion. This algorithm is fairly well known so I think everybody knows the basic code. void mergeSort(int array[], int l, ...
0
votes
1answer
69 views

Reflexive calls of objects in the same hierarchy

I am not sure how to phrase this. I believe this should have been asked somewhere, but I am unable to find it because I don't know the keywords. Basically, I have some types like this: interface Foo ...
-2
votes
1answer
3k views

How does this recursive function exit? [closed]

In the merge_sort part, there are multiple calls to the same function within the recursive. How are the other two executed when the definition holds that till a condition is false, the recursion does ...
0
votes
2answers
2k views

Implementing map with tail recursion

I am trying to solve this exercise. It is about reimplementing the map function in haskell for learning purpose. I found a solution which doesn't browse all the elements of the list (simple linked ...
3
votes
0answers
141 views

String Pattern Matching from Lookup Table - Non-Exponential Solution?

Given the problem... Given a String comprising of non-alhpabetical symbols, and a Lookup Table where a subset of those symbols may equate to a single alphabetical character, output all possible ...
1
vote
1answer
156 views

Understanding recursive solution of some algorithm

Most of the time we need to understand someone else' code for example I am studying Graph Algorithms from Sedgewick's online resources, the particular code example is taken from cycle detection ...
0
votes
0answers
47 views

Reverse lookup of data based on user input

I have an array in the format: $array = array( 0 => array( 'name' => 'Item 1', 'level' => 1, 'points' => 10 ), 1 => array( 'name' => '...
0
votes
1answer
278 views

Achieving permutation using recursion [closed]

Though I like recursions and understand it, I fail to master it! I am stuck with a problem which I know that recursion can solve, but I do not know how. I have an array of strings like: "hundred", "...
-2
votes
1answer
240 views

For loop and recursion for a new shell in C [closed]

I code a new shell in C, that could be done in several ways: Flex/bison, finite state machine, abstract syntax tree or just a tokenizer in C. Now I've written a for-loop that changes the condition of ...
3
votes
1answer
111 views

Term for the current iteration of a recursive function call

Is there a standard or widely accepted term for referring to a variable within the current call of a recursive function where the last value of the same variable is passed as an argument? I am trying ...
1
vote
1answer
182 views

Complexity of recursive calls

my brain is a little stuck as I am trying to compile an example for my blog. I am presenting an algorithm that draws a number from an array, adds it to a sum and calls itself recursively. func solve(...
10
votes
3answers
464 views

Algorithm to generate all sets of m points in n x n x n cubic lattice which are unique under symmetry

I am implementing an algorithm which is going to be quite computationally complex, and want to try to make sure I'm not doing unnecessary work. There is an n x n x n cubic lattice, e.g. if n=2 this ...