Questions tagged [recursion]
Recursion in computer science is a method of problem solving where the solution to a problem depends on solutions to smaller instances of the same problem.
4
votes
1answer
72 views
A recursive Boggle solver
`Boggle is a word game in which letters are randomly placed in a 4x4 grid
e.g:
A D Q P
N L E M
O S R T
V K J H
Words can be started from any letter and are ...
6
votes
4answers
3k views
“What is the maximum that Player 1 can win?”
This is a question that I encountered in one of the competitive coding tests. The question goes as follows:
A 2-player game is being played. There is a single pile of stones. Every stone has an ...
4
votes
3answers
386 views
Generate parentheses solution
I have coded a solution to build all valid permutations of parentheses.
My code is below.
I have a question on my code based on a comment by my PEP8 checker. It said that there was no need to ...
1
vote
0answers
16 views
JSON flattening with object duplication on array property for CSV generation
I am looking for a way to transform JSON data into a flat "csv-like" data object. In some way, I am looking to "sqlirize" a mongodb collection. I have already check some json flat libraries in NPM ...
2
votes
2answers
87 views
Generating recursive class instances from an array of splitted values by dashes (as a folder tree)
Well, I'm trying to generate the following:
Input:
...
3
votes
1answer
66 views
Get all children recursively in Entity Framework Core
In Entity Framework Core we can have recursive entities. But we cannot do an "Include" for these recursives (can we?). So I wrote a Get-method that does it for me:
...
2
votes
1answer
28 views
Performing an action which may return other actions to be performed, concurrently
I have a program which, at its core, involves repeatedly performing an action on some value, and based on that action also returning a list of new values to perform that action on. The pure version of ...
3
votes
0answers
35 views
reverse recursive search on an object with javascript - like tree search
I implemented a tree search with JavaScript.
It has below basic rules.
It will search over an array of objects which has recursive(like fractal)
If it found a according data in a leaf(the final ...
1
vote
1answer
63 views
Python program to find the factorial of a number using recursion
A factorial of a number is the product of all the integers from 1 to that number.
For example, the factorial of 5 (denoted as <...
3
votes
1answer
57 views
Matryoshka Doll Recursion
I was tasked with writing a Matryoshka doll program that manages the following:
howManyDolls : returns an integer based on how many dolls are inside the stack
howManyWearingBabushkas : returns an ...
3
votes
1answer
32 views
Efficiency of a recursive implementation of the Sieve of Erasthotenes in Python
I implemented the Sieve of Erasthotenes recursively using filter and I was wondering how efficient this implementation is and wether a non-recursive implementation ...
2
votes
1answer
44 views
Convert Tail-Call Recursive Code to Loop [closed]
So, I'm in the midst of writing a programming language interpreter in Python, and one of the problems I'm concerned about is that since I've been using a lot of recursions to implement the interpreter,...
4
votes
1answer
157 views
Return all valid paren strings with a given length
The problem is
Given a non-negative integer n, return all valid parentheses strings
with n open parens and ...
6
votes
1answer
71 views
Rendering tree of nodes as string
I'm creating a debug-view for my expression-trees. They record each operation automatically in a tree that I am transforming into string so that I can see the exact ...
1
vote
1answer
37 views
Depth-first traversal implementation in Java (by recursion)
I implemented a recursive depth-first traversal, with all three traversal modes in this function. Is this the most succinct way to write the code?
...
0
votes
1answer
38 views
Delete directory tree function
I made this function to delete a directory with all its contents recursively, will it work as expected in a production environment ? is it safe ? I don't want to wake up one day with ...
4
votes
1answer
34 views
Processing file inclusion directives using mutual recursion
I am preprocessing a set of files where one file is included in another file with an include tag like shown below:
file A
...
4
votes
2answers
103 views
Roman Numbers - The Functional Way
Yet another exercise in converting values between the decimal and roman number systems.
I have tried the functional way.
Any comments are welcome - but I'm especially interested in answers focusing ...
5
votes
1answer
96 views
A cartesian product of tuples in C++17
I would like to write a function that computes a cartesian product of two tuples in C++17 (the tuples can be of type std::tuple or ...
4
votes
1answer
198 views
Best way to performance permutations
This has been my white whale for a while, the idea is convert all the symbols to the goal symbol using all the pieces.
I did an algorithm like 5 years ago (now is lost) and reach lvl 48 but got stuck ...
2
votes
3answers
106 views
Looking for all numbers where each digit is bigger than the previous digit
This is the "Increasing Number problem", where we are looking for all numbers with \$n\$ digits where each digit is bigger than the digit before it. Or in Mathematical therms where:
$$\mathit{...
17
votes
2answers
3k views
Simple recursive Sudoku solver
My Sudoku solver is fast enough and good with small data (4*4 and 9*9 Sudoku). But with a 16*16 board it takes too long and doesn't solve 25*25 Sudoku at all. How can I improve my program in order to ...
2
votes
1answer
53 views
Replacing MIN and MAX macros with type-safe, recursive templates of variable arity
I'm currently reading Mastering Perl for Bioinformatics; I'm using the book for learning bioinformatics while implementing the code in C++. I came across a situation where I needed to use the minimum ...
8
votes
1answer
182 views
Recursive parser from Binary to JSON output
Background
I got this interview test and got declined due to not meeting their expectations, but never got a reason on what was bad and how they solved it. I want to improve and learn something out ...
4
votes
2answers
61 views
Three stage Sudoku puzzle generator
This was my first time attempting a project like this, so I figured it would improve readability, and would also just be nice If I allowed each stage to be visualized.
Also, this only generates them, ...
0
votes
1answer
137 views
Counting the number of ways to decode a string
I am working on problem where I need to decode a string..
A message containing letters from A-Z is being encoded to numbers
using the following mapping:
'A' -> 1
'B' -> 2
...
...
1
vote
1answer
101 views
The quicksort algorithm in Haskell
I am learning Haskell programming language mainly from this source. And there I have encouraged with "an elegant" realization of the quicksort sorting algorithm (the Quick, sort! section). Here it is:
...
3
votes
2answers
63 views
Capitalize a sequence of lines entered via console input and print/return
I'm running through the popular python practice exercises located at github:
https://github.com/zhiwehu/Python-programming-exercises/blob/master/100%2B%20Python%20challenging%20programming%20exercises....
1
vote
2answers
42 views
Listing ordered components, recursively
I am trying to get ordered components of an interface properly without having a local variable orderedComponents outside, and here is my current code.
Reason is because orderedComponents will be in ...
1
vote
1answer
105 views
Finding pairs that add up to a given sum, using recursion
I'm currently tasked with using recursion to find pairs that add up to a given sum. How would I make the function recursiveFixedSumPairs function more efficient and truncate this code? Also, what is ...
3
votes
1answer
31 views
Python class which chains Google translations back and forth between two languages
I created a class which creates chained translations (for example, Japanese translated to English, then back to Japanese, then to English).
Some concerns:
Is my usage of recursion good?
Is the class ...
3
votes
1answer
68 views
React.js Nested Nav Bar
This was written for a coding challenge for a company I recently starting working for. I'm looking for any suggestions on how to clean up the code, as well as any issues anyone thinks may occur as it ...
2
votes
1answer
25 views
C Recursive Opendir Wrapper to Sort Directories First (ascending/descending)
A recent post on StackOverflow about a recursive directory listing which produced an unsorted mixed file/directory list, sparked the stray thought of "What would it take to write a wrapper for the ...
2
votes
1answer
70 views
Write a function that adds two numbers stored in a linked list and returns the sum
Just for fun I did the following exercise from "Cracking the coding interview. 4th edition":
You have two numbers represented by a linked list, where each node
contains a single digit. The digits ...
0
votes
0answers
76 views
Swift Knapsack problem using bottom-down (memoization) approach
I'm solving the "unbounded" variant of the knapsack problem, meaning the repetition of items is allowed. As in the Hackerrank version of the knapsack problem, I am returning the sum nearest to, not ...
3
votes
2answers
169 views
Find the longest sub string of a word after concatenation of given words array
An Array of N words is given. Each word consists of small letters ('a'-'z'). Our goal is to concatenate the words in such a way as to obtain a single word with longest possible substring composed of ...
1
vote
1answer
165 views
Recursive react.js navigation menu
I'm very new to React.js and have to start converting an entire website at my work. It's fun, but I'm hoping to get some feedback about how I tackled building this navigation component as I don't ...
1
vote
2answers
100 views
Recursive Transversal (Python)
For a programming challenge I was doing, I needed to traverse a list of lists, and while writing the standard 2D traversal function, I thought why not generalise it, so I did. Here's my best effort:
...
1
vote
0answers
116 views
Bin-packing-problem solution using recursion
I needed to make a freight calculator and had to solve a bin packing problem. I utilized a github package.
Basically with the help of my stack overflow question I made a class Method that
Splits an ...
2
votes
1answer
61 views
Most efficient way to find spatial order from a list of tuples (Python)
I have a circle-growth algorithm (line-growth with closed links) where new points are added between existing points at each iteration.
The linkage information of each point is stored as a tuple in a ...
4
votes
2answers
82 views
Computing bezier curves of degree n with recursive functions
I have been looking at homemade CNC and have been wondering how curves are drawn, so I looked into it and found this cool article. I then decided to try coming up with a bezier curve algorithm in C. ...
0
votes
1answer
72 views
Find first repeating Char in String
Given a string, find the first repeating character in it.
Examples:
firstUnique("Vikrant") → None
...
0
votes
2answers
70 views
Get property value from object tree in a recursive way
Consider the following structure,
let condition = { and: [ { id: 3 }, { pageId: '1' } ] }
I want to get the id property value ...
2
votes
1answer
151 views
Finding peak point in an array by using divide and conquer approach
It is to find the maximum element in an array which is first increasing and then decreasing. I've tried to write my idea by using divide and conquer approach. Is there any improvable or missing point? ...
1
vote
1answer
72 views
Rectangle packing in smallest possible area
I have written a Java Program to place a bunch of rectangles
into the smallest possible rectangluar area(no overlapping and rotating).
Here is a short summary:
I calculate minArea and maxArea:
...
4
votes
3answers
150 views
Java Magic square program
Here is my improved version of my Magic square program from following this earlier version.
I also added a few comments.
Any help for improvements would be really appreciated.
...
4
votes
2answers
55 views
Replace array element with multiplication of neighbors in Scala
Given an array of integers, update the index with multiplication of previous and next integers,
Input: 2 , 3, 4, 5, 6
Output: 2*3, 2*4, 3*5, 4*6, 5*6
Following ...
3
votes
2answers
998 views
Knapsack problem - recursive approach with memoization
This post is based on the 0-1 Knapsack problem. I came across this problem in Assignment #4 of Professor Tim Roughgarden's course Greedy Algorithms, Minimum Spanning Trees, and Dynamic Programming on ...
2
votes
1answer
153 views
Java n-ary Tree class with custom made methods and nested Node class
I'm a beginner and I wrote this (working) code for n-ary tree.
The specifics:
Each node is to be built with an integer value.
Each node has a variable number of children.
The nodes should have an ...
2
votes
0answers
31 views
Finding first duplicated value from “circular” list with a recursive function
Background
This year I've taken on the challenge of Advent of Code. The second challenge of the first day is to calculate a frequency for a special device based on a series of numbers. Here's a quote ...
