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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Snail matrix in Java
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 matrix \$M_n = \mathbb{N}^{n \times n}, \$ and set the integers \$1, 2,...
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Create a snail matrix
Statement:
Create a script that, given an integer \$n\$, print 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 ...
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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 which I've implemented in Rust and published it as a crate on crates.io.
https://crates.io/crates/randevu
While I do think my code is pretty clean and idiomatic, I ...
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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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1
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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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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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Simplify matching values while comparing two sorted sets
This is in Star Basic but most likely quite a few languages would have similar structure.
I am comparing rows in two sorted sheets. I have a comparison function which returns -1 / 0 / 1 similarly to <...
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Performance optimization of traveling salesman like issue
I need help optimizing the performance of this, which is essentially similar to the traveling salesman problem, with the addition that I want to make the graph complete first, with the weight of the ...
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Implement document processing system
I have to implement a class with method that takes document:
...
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Bit vector in Java supporting O(1) rank() and O(log n) select()
Introduction
I have this GitHub repository (version 1.0.0.). It implements a rank(i) operation in \$\Theta(1)\$ time, and ...
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A recursive_find_if_all Template Function Implementation in C++
This is a follow-up question for recursive_any_of and recursive_none_of Template Functions Implementation in C++. I am trying to follow the suggestion of G. Sliepen's answer to implement ...
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Map coloring algorithm functional implementation in python
I'm an autodidact working on map coloring algorithms with backtracking, see chapter 2 of this book.
I tested this implementation with success but I'm still unsure whether it is tricking me somewhere, ...
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recursive_any_of and recursive_none_of Template Functions Implementation in C++
This is a follow-up question for A recursive_all_of Template Function Implementation in C++ and A recursive_count_if Function For Various Type Arbitrary Nested Iterable Implementation in C++. Besides <...
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Fully generic, very efficient bidirectional Dijkstra's algorithm in Java
After finding out that my previous implementations are incorrect, I decided to give it another try. I relied on this post.
(The entire project resides in this GitHub repository. Contains some unit ...
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Caesar Cipher in Swift (iOS-app)
I have implemented the Caesar Cipher in Swift and incorporated it into an iOS-app.
I guess it's formally correct. Please see the attached images, which show how the usage of the app is meant.
Here's ...
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Z-Function/ Algorithms on strings. C++
The problem:
Given a string s. For each i from 1 to |s|, find the number of occurrences of its prefix of length i in the string.
Input:
The first line of input contains an integer q (1≤q≤10⁵) — the ...
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Generating group permutations: an extended Heap's algorithm in Java
Suppose we have a sequence of sequences <1, 2> <3, 4>. There, we have two groups: <1, 2> and ...
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Heap sort optimization
I tried to optimize heap sort algorithm. Instead of recursion, I used iteration:
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Generic Algorithm X implementation with dancing links (DLX)
This is a generic implementation of Knuth's "Algorithm X" using dancing links. The whole code with a "mandatory" sudoku solver can be found at gitlab.
Regarding the scope of the ...
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Nodejs Websocket pulling new data from InfluxDB
I have a nodejs server with websocket which is pulling the new data from InfluxDB and send it to client.
The piece of code is this:
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Is this iterative inorder traversal algorithm well-known?
I was concerned about the approach in Morris traversal algorithm and came up with simpler solution that uses parent pointers in nodes.
The constraints were following:
Time Complexity: O(n)
Space ...
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Move timestamp to the next Monday 10:01 AM [closed]
I've been battling ChatGPT for hours now and can't get satisfied with this simple algorithm in TypeScript. These two (hopefully correct) TypeScript+ReactNative solutions should move the timestamp ...
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Gaussian elimination algorithm in C++
Given:
j-g-h-i=0
a+b-c-j=0
c+i-d-e=0
e+g-f=0
And known:
a=10
b=7
d=3
e=2
f=3
j=14
I want to solve this (or similar equations) ...
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