Questions tagged [algorithm]
An algorithm is a sequence of well-defined steps that define an abstract solution to a problem. Use this tag when your issue is related to algorithm design.
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Leetcode: Number of Islands - BFS (Queue vs Recursion)
I was playing around with leetcode's Number of Islands.
As per the challenge's description:
Given an m x n 2D binary grid grid which represents a map of '1's
(land) and '0's (water), return the ...
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Can I use only mutex and condition variable Instead of the Banker's Algorithm?
I've been studying the Banker's Algorithm and was curious if I could implement a similar resource management system using only Mutex and Condvar. The code I wrote is a synchronization program that ...
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C standard input escape sequence replacer program
I've been recently trying to learn C from the K&R Book The C Programming Language.
Currently I'm working on my skills on program control flow, which includes case statements.
To train my skills ...
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Dial's heap in Java for integer priority queues
(The entire project is here.)
Intro
I have this priority queue data structure for non-negative integer priority keys. I recall that it is called Dial's heap.
Code
Implementation
...
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Fast and precise summation of random numbers
I'm trying to first formulate this challenge.
In short, we want to sum up an stream of random numbers with the following objective:
The objective is "simply" to sum up as many sequences as ...
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Optimizing a Function to Check Pronic Numbers in JavaScript
I've written a function in JavaScript to check whether a given number is a Pronic number. A Pronic number, also known as an oblong number, rectangular number, or ...
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A machine learning model for predicting bit strings in Java
I have this GitHub repository (BitPredictor.java). Basically, I tried to harness a machine learning model for predicting bit strings. I have implemented it to the best of my understanding and have ...
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Write a Swift-function, which computes the Digital Root
Task: Write a function, which computes the Digital Root of a given number n.
Here's the solution, which I developed:
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Rust implementation of a BTree
I'm studying rust, and I decided to implement a BTree as a way of learning the language.
Can anyone give me suggestions on the code?
As the language has no inheritance, and we must replace it with ...
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Clique Connect: minimum spanning tree
Problem Statement
You are given a weighted undirected graph G with N vertices, numbered 1 to N. Initially, G has no edges.
You will perform M operations to add edges to G. The i-th operation (1≤i≤M) ...
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Rust implementation of an algorithm I invented (RANDEVU) #2
I came up with an algorithm and created a Rust implementation of it.
I've already posted it for code review previously but created another post since I've made many changes to it, including the ones ...
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Point in polygon (with holes) algorithm
I am working on a CAD addon, where I needed a function() which tells me if the point is inside a polygon or not. I have already found some good solutions for it, but none of them worked for me ...
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Codeforces: D2. Counting Is Fun (Hard Version)
The code works okay for the following problem.
Problem
An array 𝑏 of 𝑚 non-negative integers is said to be good if all the elements of 𝑏 can be made equal to 0 using the following operation some (...
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Image Rotation with Shear Transformation in C++
This is a follow-up question for Image Rotation and Transpose Functions Implementation in C++ and An Updated Multi-dimensional Image Data Structure with Variadic Template Functions in C++. I am trying ...
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Snail matrix in Java - version III (generalizing)
Once again, in the previous version,
Alexander Ivanchenko helped me with his awesome answer.
Now, I have improved the toString() and, also, generalized the class ...
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Snail matrix in Java - version II
(This post is the continuation of Snail matrix in Java. Also, this post has an continuation.)
As previously, a snail matrix is any square matrix \$M_n = \mathbb{N}^{n \times n}\$ with cell elements ...
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Snail matrix in Java
(This post has an continuation: Snail matrix in Java - version II.)
Inspired by this post, I decided to solve that problem in Java. The idea is to decide on an \$n \in \mathbb{N}\$, create a square ...
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Create a snail matrix
Statement:
Create a script that, given an integer \$n\$, create a square matrix of dimensions \$n \times n\$ with the numbers from \$1\$ to \$n^2\$, arranged in a snail pattern.
Example:
...
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Optimizing Perfect Hash Table Implementation in C for Improved Performance
I wrote code that implements perfect hash table, according to its description in the book "Introduction to Algorithms by Thomas H Cormen", but the code does not pass time tests in contest. I ...
user282352
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I wrote a O(log N) code for largest element in an array today but is this an already existing way to find max element in an array? [closed]
Largest element in an array's most optimal approach. The code I have written has passed all test cases in https://www.naukri.com/code360/problems/largest-element-in-the-array-largest-element-in-the-...
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Leetcode: Largest Number
I was trying out leetcode's Largest Number.
As per the challenge's description:
Given a list of non-negative integers nums, arrange them such that
they form the largest number and return it. Since ...
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Implementation of Kirkpatrick-Seidel convex hull algorithm and comparing against Jarvis-March
Introduction
I wanted to implement the Kirkpatrick-Seidel(KPS) convex hull algorithm and chose Rust as my language. I referred to the original KPS paper and tried to implement as closely it as ...
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Centre of mass based TSP solution (2)
I updated the code to a working state. My previous question. Even if this code working I wonder if I can write this code in a more efficient way. Maybe less for loops Etc.
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Image Rotation and Transpose Functions Implementation in C++
This is a follow-up question for Gaussian Fisheye Image Generator Implementation in C++ and An Updated Multi-dimensional Image Data Structure with Variadic Template Functions in C++. I am trying to ...
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Creating an O(n) algorithm for an array of integers
To avoid plagiarism in my university, I am going to modify the problem.
Henry likes to jump from building to building. The heights of each building are given as a list of H numbers. We also number ...
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Colorful Subgraph Dynamic Programming Solution and a Naive One
Given a graph \$G(V, E)\$ with vertices \$V\$ and edges \$E\$, where each vertex is associated with a single color from a set of colors \$C=\{1, 2, ..., k\}\$, we define the following problem:
Problem ...
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Thread pooled bidirectional breadth-first search in Java for graphs with slow node expansion - part I/II: the algorithm
(This post has part II/II.)
Intro
This time, I have this GitHub repository. The idea is that if the graph node expansion is slow (for example, in the case where you ask a web server to return some ...
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Gaussian Fisheye Image Generator Implementation in C++
This is a follow-up question for An Updated Multi-dimensional Image Data Structure with Variadic Template Functions in C++ and Three dimensional gaussian image generator in C++. I am trying to make a ...
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Efficient least-significant digit (LSD) radix sort for int and long keys in Java - iteration II
This post elaborates on Efficient least-significant digit (LSD) radix sort for int keys in Java. This time, I made mild corrections to my code and provided the radix sort for ...
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Shunting yard calculator in C
I'm new to C, and made this program that parses a string expression into a linked list post-fix expression, and then evaluates it, without parsing the string beforehand. Wondering if there is anything ...
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Efficient least-significant digit (LSD) radix sort for int keys in Java
(This post has a continuation post.)
This one is my attempt at LSD radix sort:
Code
com.github.coderodde.util.LSDRadixsort.java:
...
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Sorting songs with the ability to save and resume partial sorts
I listen to a lot of music (~4k h/y) and managing thousands of songs is a bit of a challenging.
To improve my listening experience I want to better organize my collection.
One thing I want to do is ...
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Filling a buffer with a repeating pattern of N bytes
My program will clear the screen to a 24bit RGB color; in other words, it will fill a buffer with a repeating pattern of 3 bytes. So I wrote patternMemcpy to perform this operation efficiently*. It ...
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Step-by-step re-arranging of a string with randomized characters
A sloppy code featuring algorithms to efficiently randomize the characters of a string "Hello C" and then print out in the console the re-arrangement process for every character.
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Leetcode: Steps to Make Array Non-decreasing
I was trying out leetcode's Steps to Make Array Non-decreasing
As per the challenge's description:
You are given a 0-indexed integer array nums. In one step, remove all
elements nums[i] where nums[i ...
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RANDEVU - Rust crate implementing a simple algorithm I invented
I've created a simple algorithm, implemented it in Rust, and published it as a crate on crates.io.
https://crates.io/crates/randevu
My code seems pretty clean and idiomatic to me, but I'd like to know ...
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An Updated recursive_transform_reduce Template Function with Unwrap Level Implementation in C++
This is a follow-up question for A recursive_transform_reduce Template Function with Unwrap Level Implementation in C++. To fix the issue mentioned in G. Sliepen's answer, I updated the test cases and ...
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A recursive_transform_reduce Template Function with Unwrap Level Implementation in C++
This is a follow-up question for A recursive_transform_reduce Function for Various Type Arbitrary Nested Iterable Implementation in C++ and recursive_invocable and recursive_project_invocable Concept ...
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Find min sum for indices to match equation
I want to reduce time complexity of my code:
I have an array of integers arr say [1, 2, 3, 6, 67]
I have an equation :
a*x+b*y=z, I can use the array values in this ...
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Skip list -based Map in Java
Now I have this result.
Code
com.github.coderodde.util.SkipListMap.java:
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Leetcode : First Missing Positive
I was trying out leetcode's first missing positive.
As per the challenge's description:
Given an unsorted integer array nums, return the smallest missing
positive integer.
You must implement an ...
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First order hidden Markov model with Viterbi algorithm in Java
Introduction
A first order HMM (hidden Markov model) is a tuple \$(H, \Sigma, T, E, \mathbb{P})\$, where \$H = \{1, \ldots, \vert H \vert\}\$ is the set of hidden states, \$\Sigma\$ is the set of ...
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Path Compression Algorithm in C#
Let's consider a simple graph represented by the following edges, where true indicates a visible node and false indicates a non-visible node:
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A simple find function with concepts
I have written the following simple find function template that does a linear search.
...
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Semi-dynamic range minimum query (RMQ) tree in Java
Introduction
I have this semi-dynamic range minimum query (RMQ) tree in Java. It is called semi-dynamic due to the fact that it cannot be modified after it is constructed. However, the values ...
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1
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c++ quicksort pivots
Is this code for quicksort using the first index as a pivot correct?
Also if I want to use the last or middle index as a pivot how would the whole code change?
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A recursive_find_if Template Function with Unwrap Level Implementation in C++
This is a follow-up question for A recursive_find_if_all Template Function Implementation in C++, A recursive_all_of Template Function Implementation in C++ and A recursive_all_of Template Function ...
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Beginner's attempt at TicTacToe
This is my attempt at making a basic TicTacToe game to play against another human player or a computer controlled opponent. The project was a lot harder for me than I initially thought it would be!
I ...
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Bit vector in Java supporting O(1) rank() and O(log n) select() - follow-up
(This post is the continuation of Bit vector in Java supporting O(1) rank() and O(log n) select(). It resides here (version 1.0.1).)
Basically, I have implemented everything harold suggested, except ...
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