Questions tagged [performance]

Performance is a subset of Optimization: performance is the goal when you want the execution time of your program or routine to be optimal.

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185
votes
4answers
30k views

Dijkstra path finding in C# is 15x slower than C++ version

I'm implementing Dijkstra's algorithm with a priority queue for a game I'm developing in Unity with C#. I was a bit disappointed with the performance, so I decided to port the code to C++ and see if ...
108
votes
4answers
20k views

Celebratory fireworks animation

To celebrate an important event, I hastily cobbled together an HTML canvas-based animation. A few concerns I have include: Performance: Does it run reasonably smoothly on most modern machines? How ...
98
votes
9answers
37k views

Fastest way to clamp an integer to the range 0-255

I'm working on some image processing code that can generate pixel values outside of the normal range of 0 to 255, and I'd like to clamp them back into the valid range. I know that there are saturating ...
84
votes
5answers
15k views

Load fifty million integers as quickly as possible in Java

I am working my way through Project Euler. Many of the problems deal with prime number calculations: this is the type of code that can be extracted into a separate class and reused. While calculating ...
79
votes
1answer
3k views

Siamese neural network

I have been studying the architecture of the Siamese neural network introduced by Yann LeCun and his colleagues in 1994 for the recognition of signatures ("Signature verification using a Siamese time ...
57
votes
4answers
2k views

Chat bot for posting recent answers

I am the half-robot side of syb0rg that will be posting the recent answers of Code Review to the CR Answers chatroom. Here is the list of review suggestions I would like, in order of preference: ...
53
votes
9answers
12k views

Project Euler problem 1 in Python - Multiples of 3 and 5

I'd like suggestions for optimizing this brute force solution to problem 1. The algorithm currently checks every integer between 3 and 1000. I'd like to cut as many unnecessary calls to ...
50
votes
3answers
3k views

Analyzing Minesweeper Probabilities

Calculating probabilities in Minesweeper might sound like an easy task, but I've seen so many probability calculators that's either incorrect, horribly slow, or with ugly code (or all of them) so I ...
44
votes
7answers
16k views

Mandelbrot image generator and viewer

This is a C++ program which outputs a Mandelbrot fractal image in a graphics window and lets the user zoom and pan around the image, generating a new image each time the user does so. I'm using SFML ...
44
votes
3answers
6k views

Benchmarking things in C#

I needed a better way to benchmark code, because, well, rewriting the same benchmarking code every time I need it is just...well...unpleasant. So, here's a class which does just that, it runs an <...
41
votes
2answers
74k views

Finding the closest point to a list of points

I'm trying to find the closest point (Euclidean distance) from a user-inputted point to a list of 50,000 points that I have. Note that the list of points changes all the time. and the closest distance ...
40
votes
2answers
230k views

Converting DataTable to List of class

I am using ExcelDataReader to import an Excel file to a dataset. Example Excel table: ...
38
votes
4answers
6k views

Ultimate Tic-Tac-Toe in C

Here is my attempt at the UTTT code-challenge (in response to the the Weekend-Challenge Reboot). Here is what I would like critiqued: I tested the code a few times for bugs, but I may have missed ...
37
votes
4answers
7k views

“How are you spending your time on the computer?”

I've made a Windows Forms application to track all of the processes running on my machine and it also saves the time an application is "active", an active application is the one that is on focus ...
36
votes
2answers
5k views

Quicksort implementation seems too slow with large data

I've written a program to compare different sorting algorithms with the array size being 10, 1,000, 100,000, 1,000,000 and 10,000,000. I, of course, expect Insertion to win out on 10 and merge heap ...
36
votes
9answers
12k views

Copying 80 bytes as fast as possible

I am running a math-oriented computation that spends a significant amount of its time doing memcpy, always copying 80 bytes from one location to the next, an array ...
35
votes
7answers
4k views

Increase performance creating Mandelbrot set in python

I created a program in python that generates an image of the mandelbrot set. The only problem I have is that the program is quite slow, it takes about a quarter of an hour to generate the following ...
35
votes
3answers
2k views

Voxel World Optimization

This is not related to a Minecraft clone. I am currently writing a turn-based strategy game like Final Fantasy Tactics. The game is played on floating voxel-style islands, which are generated from ...
34
votes
9answers
7k views

Solving the Lazy Hobo Riddle

I would like help in optimizing this calculation, which is from the Lazy Hobo Riddle: There once were 4 hoboes travelling across the country. During their journey, they ran short on funds, so ...
34
votes
6answers
13k views

AES Implementation in C++

I've implemented AES (128, 192 and 256) in C++ and I'm looking to improve the code to make it not "DIY-crypto-bad", if at all possible. I've also been trying to optimize my code, and so far I've ...
34
votes
5answers
5k views

Recording Audio Continuously in C

As an ongoing little side project of mine, I've been working on recording audio in c. You can the code's progression by looking at past versions (V1.0, V2.0). I've found that my past versions were ...
32
votes
11answers
2k views

Too many loops in Drawing App

I have a method that has a lot of loops: ...
32
votes
3answers
7k views

A* pathfinding algorithm too slow

I'm trying to make a pathfinding algorithm for my project. I need it for a simulation and I need it to be fast!!! I watched a few videos explaining the algorithm online and came up with the code ...
32
votes
7answers
6k views

Project Euler #7 10001st prime

I decided to start working on the Euler project exercises. I'm doing fine for now but the seventh problem is running quite slow and I can't think of anything to make it work faster. It takes around ...
31
votes
5answers
47k views

Brute Force Algorithm in C

This is a simple brute force algorithm that I have programmed in C. All the program does is print out every possible combination of the given alphabet for the ...
30
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10answers
14k views

Sorting large 1GB file with 100 millions numbers using merge sort

My task is to sort 1GB file with 100 million numbers using merge sort without recursion. My idea is to split file into 4 pieces, then to 2 and at the end to one file. ...
30
votes
7answers
53k views

Password validation in Java

I just wrote this password validation code function that checks to see if a password will be accepted in AD or not. I'm not sure this is the best way to do it, but for now it works fine. I would love ...
30
votes
6answers
6k views

Counting rows in a CSV file that correspond to a database row, each with a million records

I have two DataTables: dt: is populated from a CSV file with over 1.7 million rows dataStructure.Tables["AccountData"]: is ...
30
votes
4answers
15k views

Recording audio in C

Please note there are newer revisions of this code, one here, and one here for continuous audio recording. This is a program I wrote as a .wav audio recording library for Linux. It was developed on ...
30
votes
6answers
3k views

Aliens at the train

I solved this problem on SPOJ: The aliens have arrived to Earth and everything is in harmony, the two races can live together. However, one specific Female Alien does not want to see humans on ...
30
votes
3answers
2k views

Regex to parse horizontal rules in Markdown

I'm the current maintainer of Showdownjs, a markdown parser off which PageDown (stackexchange's markdown parser) is based on. Showdown uses the following regex to parse horizontal rules: ...
30
votes
5answers
27k views

Int overflow check in Java

I have a piece of code that takes a couple of integers and check if performing an addition on the inputs would result in an overflow. I was wondering if this code is SOLID: ...
28
votes
8answers
44k views

Using a for-loop or sleeping to wait for short intervals of time

I need to wait for short intervals of time in my program, but I really don't want to include unistd.h just to use sleep, so I'm ...
28
votes
8answers
4k views

Project Euler Problem 45

As a self-teaching Python beginner for almost 4 months, I have mostly been doing online challenges including Project Euler problems. Problem 45 asks: Triangle, pentagonal, and hexagonal numbers ...
28
votes
4answers
2k views

Extending Sieve of Eratosthenes beyond a billion

For MAX value of 1000000000 (\$10^9\$), it takes about 45 seconds to reach the line where it prints "done". How can I speed this ...
28
votes
2answers
102k views

Integer to Alphabet string (“A”, “B”, …“Z”, “AA”, “AB”…)

So this question is prompted by two things. I found some code in our source control doing this sort of things. These SO questions: https://stackoverflow.com/questions/297213/translate-an-index-into-...
28
votes
3answers
25k views

Perm-Missing-Elem: 100% functional score, but only 60% performance

I cannot figure out why I didn't get 100% success from the Codility's Perm-Missing-Element test even I solve with \$O(n)\$. I will appreciate any advice/answers. You can see the problem, my code, and ...
28
votes
6answers
4k views

DailyProgrammer 284: Wandering Fingers

Description Software like Swype and SwiftKey lets smartphone users enter text by dragging their finger over the on-screen keyboard, rather than tapping on each letter. You'll be given ...
28
votes
1answer
65k views

Pack and unpack bytes to strings

I need to write a function that "packs" an array of bytes (integers between 0 and 255) into a string. I also need to be able to perform the reverse operation, to get my byte array from the string that ...
28
votes
2answers
58k views

Recursion vs iteration of tree structure

Some recursive code is part of a particularly slow path of a project. Out of curiosity I was playing around with reimplementing the code using stack context iteration instead of recursion. Below are ...
27
votes
6answers
9k views

Matching a generated string of random letters to an input

I made a program in Python and wanted it to be faster, so I wrote it on C# because it's compiled. To my surprise, the Python program is much faster. I guess there is something wrong with my C# code, ...
27
votes
5answers
10k views

Custom indexOf() without String methods

I created my own indexOf function. I was wondering if anyone could help me come up with a way to make it more efficient. I am practicing for interviews so the catch ...
27
votes
5answers
4k views

C++ logging library

I am creating a logging library in C++, and I wanted your opinion on code quality and performance within some methods. You may ask why yet another logger - the answer is simple. This logging library ...
27
votes
1answer
952 views

Rust Brainfuck interpreter

I took the code from kostyas benchmarks for the Rust Brainfuck interpreter and tried to optimize it. There is also a discussion on Reddit about the poor performance of Rust in the Benchmark. Before ...
26
votes
1answer
5k views

Improving the Java UUID class performance

I am looking to submit the following code (adapted to fit into java.util obviously) which significantly improves performance and reduces useless allocations of <...
25
votes
6answers
6k views

Close to the metal C++ Palindrome Program

I am attempting to reinvent the wheel by writing my own palindrome checking program in C++, using only basic loops and mathematical operations. I have arrived at a solution, but was wondering if it's ...
25
votes
4answers
83k views

Is the LINQ version faster than the foreach one?

Since I don't know how LINQ works under the hood, I can't decide what version is best to use in term of rapidity of execution. I've done some testing with my testing data (Point Cloud) but I can't see ...
25
votes
1answer
992 views

How can I make my stack monad faster?

I made a stack monad that lets one manipulate and control values on a stack. I want to know if it's correct (it seems correct), how to make it faster, and how I could detect stack overflows without ...
25
votes
0answers
509 views

Definitional Returns. Solved. Mostly

I have made the bold claim that a longstanding problem in Rebol is "now solved"...that of "definitional returns". But of course, such claims need some peer review, and there's always some new trick ...