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.
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Recursive Java Red-Black Tree
I've made an attempt at a recursive Red-Black tree in Java. I realise that some of my code could be condensed but I tried to favour readability with this code as Red-Black trees can be somewhat ...
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1answer
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How can I reduce this code javascript code so it's not as repetitve?
I have a function which goes through every name in an object. This object has an array parameter materials which holds other objects. Those objects have the same array parameter which hold more ...
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Spiral Scanning for matrix using recursion
I have written code for scanning an N x M matrix in spiral order using a recursive function.
It uses 5 parameters - including 2 extra variables:
call to keep ...
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0answers
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Knight's Tour with Heuristics
When someone suggested that I solve Knight's Tour, I did so with heuristics and recursion.
It takes a lot of time to solve even a 8x8 board:
N-A1
N-C2
N-E1
...
N-E6
N-F4
Time ...
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3answers
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N-Queens - Brute force - bit by bit
A discussion in The 2nd Monitor made me realize I had never 'solved' the N-Queens problem. Additionally, as I read up on it, I realized that the 64-squares in a chess board would work well if ...
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Project Euler #14 — longest Collatz sequence
I was reading this question and realized that I didn't know Python well enough to critique the algorithm. So I wrote a Java solution instead, which is inappropriate for that question. Since there's ...
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2answers
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Parse a tree & return the various paths
Input:
{ 1: [2,3], 2:[4], 3: [5,6], 4:[6] }
Expected output:
[[1, 2, 4, 6], [1, 3, 5], [1, 3, 6]]
My Code:
...
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1answer
51 views
A prime number sieve using recursion
Out of curiosity, I built a recursive Sieve of Eratosthenes in Python and I was wondering how it could be improved for efficiency and how it can improved to be aligned with python best practices.
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1answer
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'Tis the season for gift-wrapping
When reviewing a Graham scan convex hull algorithm implementation, I wrote the following function in an answer:
...
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AI for an online contest
I'm actually creating an AI for the online contest Vindinium. The fact is that's also an exam for my school because I'm going to have a note with that work.
I created an AI based on ants pheromones ...
12
votes
2answers
180 views
My recursive parser is wet behind the ears (well, it's not DRY at least)
I have an issue opened on GitHub since mid-November, to refactor & DRY up the Rubberduck Parser module (the idea is to model the code in a VBA project or code ...
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Calculating a specific entry in a Pascal’s triangle recursively
Our task was to calculate the entry of a Pascal’s triangle with a given row and column recursively. The triangle was specified in a way that the tip of the triangle is ...
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votes
1answer
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Rotate image 90 degree clockwise recursively
Previous question:
Rotate image 90 degree clockwise
In this code I have used tail recursive, which is bad. Time complexity is still \$O(N^2)\$, which is worse-case. The only good part is memory ...
3
votes
1answer
49 views
Getting rid of extra test during initialization of loop/recursion
I'm reluctant to ask this question. My code below works, it's intelligible, and it seems reasonably efficient. It's just that there's a trivial, nitpicky issue that's driving me crazy. The function ...
5
votes
1answer
61 views
Create a tree recursivly
I want to create a Treeview in C# which will group file by prefix (here the prefix is a marked by the separator _). The following files should give this tree:
...
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2answers
154 views
Rotate an image (2D array) by 90 degrees recursively with low memory usage
I'm looking for comments on coding style, passing arguments, ...etc.
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1answer
62 views
Recursive functions
I am using the following code which recursively executes function findWpisInZone(), code works fine, I just wondering if there is any better way to do it in JS,
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Object storing and retrieving using wildcard identifier
I'm writing an interpreter for a scripting language which allows objects to:
Have an alias
Be referenced using a wildcard
Contain child objects
Combination of all three above
For example:
...
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votes
1answer
40 views
Memoization for calculating minimal traversal distance within a positive matrix
The code below is for calculating the minimal traversing distance from the top left point of the matrix to the bottom right point of the matrix.
GitHub
Here is the core functionality. Please note ...
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3answers
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AudioMetaTagger: recursively read files and gather metadata
So the idea is to read metadata recursively in a chosen directory, load their metadata and display it into a table.
Here is the simplified example of what I am doing.
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votes
3answers
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Removing nested blocks from a string
I wrote this function in scala that uses tail recursion to remove nested blocks from a text.
Usage examples:
...
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votes
2answers
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Brainfuck interpreter in Haskell
Okay, so I just started learning Haskell around a week ago and this is my first real program that I worked on all of yesterday with a lot of help from IRC. I know that using indicies and arrays is not ...
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2answers
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Simplifying this factorial function
def factorial(t,n):
if n == 1 : return t
else: x = (t * (n-1))
n = n-1
return factorial(x,n)
print factorial(6,6)
I can't seem to figure out ...
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votes
2answers
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Validating a Binary Search Tree
This is an implementation of a function to check the property of a Binary Search Tree, that is:
the key in any node is larger than the keys in all nodes in that
node's left subtree and smaller ...
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votes
0answers
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GOF Composite Design Pattern Implementation Using Modern C++
After reading about the composite pattern from the GOF design pattern book, I thought to re-implement the code mentioned in the motivation section using the modern C++ concept/idioms. Below is the ...
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4answers
265 views
Get the environment variable's value
I've written a function which can get the environment variable's value. The input parameter would one of the following:
${machine}/bin
...
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votes
2answers
48 views
Lopsided Trees and Recursion
The original problem is:
Define the height of a binary tree to be the number of nodes in the
longest path from the root to a leaf. The empty tree is considered to
have height 0. A node is ...
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3answers
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Miller-Rabin Recursive Primality Test
I'm working on a primality test and have written a recursive function that returns the value of the function
\$b^{q-1} \bmod q\$
where \$3<= q <= 32000\$
Is there any way to speed up ...
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votes
1answer
524 views
Nsum problem: find all n elements in an array whose sum equals a given value
I am implementing the algorithm for the following problem with Python. I am pretty new to Python, so I want to listen to any advice that improve my coding style in a "pythonic" way, even about naming ...
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votes
2answers
345 views
Simple factorial program using recursion
Two concepts I realized I needed to understand and use more are recursion and Exceptions. Thus, I combined both in the following program. Although it began with a focus on using recursion it became ...
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2answers
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3answers
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Recursive linear search - branch style and layout
Is my layout of the if/else statement reasonable?
It feels clumsy to me to spread the termination condition over the first three lines of the function. Can I ...
2
votes
1answer
61 views
Time complexity of 0/1 Knapsack challenge
The code gives correct output. How do I calculate time complexity for code like this?
The program finds all the combinations of items and sees if the combination gives the max profit. If the last ...
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vote
1answer
37 views
Decoding an element list
I have a function which I am calling an infinite number of times (or until a condition is met). The problem with this recursive function is that on a higher level, it is called by a worker thread ...
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1answer
1k views
Implement a string in reverse using pointers and recursion
I'm trying to reverse a string using pointers and recursion, and I send it a char array. Is this the best way, or is there a better one?
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3answers
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Merge Sort Implementation in Java (that seems slow…)
I decided to write my own implementation of merge sort. Here is the code:
...
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1answer
113 views
Cutting stock recursion
This problem is identical to the one here:
Suppose that you have been assigned the job of buying the plumbing
pipes for a construction project. Your foreman gives you a list of the
varying ...
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votes
1answer
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Using brute force to find an energy optimal path for a given amount of time
The code below implements a brute force method to find an energy optimal path for a given amount of time t_aim using recursion (the recursion function is ...
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votes
1answer
66 views
Process a line in chunks via Regular Expressions with Ruby
I'm writing a Ruby script to reverse engineering message log files. They come from an external system with the following characteristics:
Each line of the log file has at least one message.
Each ...
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votes
1answer
66 views
Efficiently creating a menu consisting of multi-level structure
I was asked to modify existing code to allow multi-level page structure. Each page can have one parent, and one page can have multiple children.
I will present following code. My question is is there ...
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votes
1answer
2k views
Print all possible combinations of size r, from an array of size n
This is my working solution for the following problem: given an array of integers of size n, print all possible combinations of size r.
Before I proceed to the solution, I have the following ...
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3answers
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Recursive, nested list traversal
Given a nested list of strings (which may contain other nested lists), print the contents of the list and the corresponding depth.
Here is my solution:
...
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1answer
91 views
Queens placement
The code below is intended to be a learning material for high school intermediate programming class, as an introduction to recursion and backtracking. I was thinking of rook placement and found it too ...
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votes
1answer
2k views
Recursive function that generates the permutations of a string
I am looking for a review of my recursive function that generates the permutations of a string. Are there better ways to do this?
...
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1answer
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