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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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 ...
7k views

Sieve of Eratosthenes - Python

I've been doing a lot of Project Euler lately and just wanted to make sure my implementation was as good as it could be. Does anyone have any suggestions to speed this up? ...
176 views

Hand Coded State Driven Lexical Analyzer in C With Unit Test Part A

This code review is presented in 3 questions due to the amount of code: Part A (this question) contains the Lexical Analyzer and the main portion of the unit test code. Part B contains the lower ...
13k views

Optimize Conway's Game of Life

I have coded up an implementation of Conway's Game of Life and I have a performance bottleneck in it which I wish to be optimized. The main logic is in the Universe ...
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Project Euler Problem 12 - triangle number with 500 divisors

I've just done Problem 12 of Project Euler: What is the value of the first triangle number to have over five hundred divisors? The $N$'th triangle number is the sum of all natural numbers ...
111 views

A recursive_transform Template Function with Execution Policy

This is a follow-up question for A recursive_transform for std::vector with various return type, A recursive_transform Function For Various Type Nested Iterable With std::variant Implementation in C++ ...
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Parser written in PHP is 5.6x faster than the same C++ program in a similar test (g++ 4.8.5)

I'm absolutely dumbfounded by this. I was trying to demonstrate to myself how much faster C++ is than even modern PHP. I ran a simple CSV parsing program in both that have the same output. The CSV ...
59k 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 ...
70k 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 ...
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Solving 15 puzzle

I'm trying to solve 15 puzzle using A* algorithm, but something really bad goes on in my get_solution() function that ruins performance. I guess there is a too much ...
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Find the binary gap of a number N

For example, number 9 has binary representation 1001 and contains a binary gap of length 2. The number 529 has binary representation 1000010001 and contains two binary gaps: one of length 4 and one of ...
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How can I quickly find unique list items?

I use the loop-every-single-list-item approach to filter out unique elements in a given list, which tends to be very inefficient way as a list grow in size, or as function call frequency increases. ...
273 views

Knights Tour - Improved Refactored Recursive Breadth First Search for

The development and testing was performed on a Dell M6400 Laptop (Intel Core 2 Duo) running Centos 7, g++ compiler version 4.8.5, compiler switches -O3 -std=c++0x -D__cplusplus=201103L. (machine ...
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Efficiency of Project Euler problem 35

The number, 197, is called a circular prime because all rotations of the digits: 197, 971, and 719, are themselves prime. There are thirteen such primes below 100: 2, 3, 5, 7, 11, 13, 17, 31, 37, 71, ...
856 views

Recursive Breadth First Search for Knights Tour

This was written as an experiment in performance, based on another question here on CodeReview. Input into the algorithm is the number of squares on one edge of the chess board, the point of origin, ...
78 views

Hand Coded State Driven Lexical Analyzer in C With Unit Test Part C

This review is presented in 3 questions due to the amount of code: Part A contains the Lexical Analyzer and the main portion of the unit test code. Part B contains the lower level unit tests called ...
83 views

A recursive_transform Template Function Implementation with std::invocable Concept and Execution Policy in C++

This is a follow-up question for A recursive_transform Template Function Implementation with std::invocable concept in C++ and A recursive_transform Template ...
13k 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 ...
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Finding the sub-array with the maximum sum - my approach

This is the code I ended up with that implements the approach I described in a recent answer to another question about the same problem The basic idea here is to not loop through more things than ...
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Coin Change: Minimum number of coins

Problem: You are given n types of coin denominations of values $v(1) < v(2) < ... < v(n)$ (all integers). Assume $v(1) = 1$, so you can always make change for any amount of money $C$....
431 views

Sequence-based enumeration of permutations in lexicographic order

This is follow-up on On Knuth's "Algorithm L" to generate permutations in lexicographic order, where I presented the following method to enumerate all permutations of array elements in ...
881 views

Matrix of articles and authors from large JSON dataset

Given the following JSON data containing 4 articles by 4 different authors: ...
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Printing longest sequence of zeroes

I am doing a coding exercise in codility and I came across this question: A binary gap within a positive integer N is any maximal sequence of consecutive zeros that is surrounded by ones at both ...
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The Beauty and the Strings

This originally appeared in Facebook's hacker cup 2013. Solving it was fun, though I find myself looping through similar data quite often. Challenge: Print the maximum beauty of strings. ...
977 views

Timing analysis of many test cases in Python

I am learning about timing analysis in Python. I used time module before it was pointed out that timeit module would be better ...
575 views

MergeSort performance

Do you see any inefficient parts with the following code? On internet I see 30 ms for 100.000 integers but I can sort 100.000 integers in 300ms. The data is random. I am using late 2013 macbook pro so ...
2k views

Generating frequency tables based on CSV dataset

I am working on a project which crunches plain text files (.lst). The name of the file names (fileName) are important because I'...
241 views

Simple neural-network simulation in C++ (Round 2)

Intro Yesterday I posted this question. Since then, I've updated my code to incorporate these suggestions. I've also removed the dependence on C++11. Finally, I've made the following changes that ...
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Non generic Skip List implementation in C++ Version 2

Edit: This code was reworked and repostetd under a new question: Generic Skip list implementation in C++ Version 3 This is a follow up of: Non generic Skip List implementation in C++ If you don't ...
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Mixed Duo String Generator

I've create a program that finds mixed duo within a string. It removes characters from a string that do not form the first mixed duo. It does not rearrange the order of the string, it ony remove ...
517 views

A Specific Combination

This code is going to be included in my Minesweeper Probabilities project. (so far it only exists on the develop-branch) The purpose is to return a specific combination, let's say for example that ...
603 views

Class Seperation vs Polymorphism

I'm interested in optimizing my code. Can someone help me understand the best way to trim this code down with DRY methodology? So I've got these two classes here preforming WMI queries on two ...
47 views

Hand Coded State Driven Lexical Analyzer in C With Unit Test Part B

This review is presented in 3 questions due to the amount of code: Part A contains the Lexical Analyzer and the main portion of the unit test code. Part B (this question) contains the lower level ...
2k views

Simplifying and optimizing factors and prime factorization generator

My first algorithm for finding the factors of a number was pretty slow and horrible (it started at $O(n^2)$, where n was not even the inputted number), but I eventually came up with this new code. ...
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C# Tool to Generate MS Word Document Mailbox List From MS Excel

There is now a Follow up question to this question. Abstract The VBA solution didn't work on the clients computer because Office 2010 Starter Edition doesn't support VBA. I decided to try a C# ...
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Challenge: Write a program which determines the largest prime palindrome less than 1000. The answer is 929, and my program correctly finds and prints this, but actually ended up being more complex ...
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Common Unit Testing Code – Follow Up

This question is a follow up question to the Common Unit Testing Code portion of my lexical analyzer questions. My primary concern is the code in the header file and the C source file that implements ...
813 views

Fast Prime Sieve (Python Implementation)

A modified version of the prime sieve. I actually doubt it could be implemented any faster, but I might be wrong: ...
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Changing the formatting of sheets

This my program to change the formatting of sheets in different folders. I have over 5000 files in one folder and it is taking up to three hrs for one folder and there are multiple subfolders in the ...
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 ...
118k views

I am just coding some classic brute force password cracking program, just to improve myself. I've explained how my program works at the start of the code. Check some of those screenshots to ...
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Sieve of Sundaram for Project Euler 7: Python implementation slower than C++ and R

A friend of mine recently started learning R, and she complained to me that R is very slow. She was working on Project Euler Problem 7, which asks for the value of the 10001st prime number. For ...
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Large Number Limit Extravaganza

I am writing a program that computes $$n-n \cdot \left(\prod_{i=1}^n (1-\frac{1}{p_i})\right)$$ which is rewritten in my code as: \left(1-\left(\prod_{i=1}^n(1-\frac{1}{p_i})\right)\right) \cdot ...
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Sieve of Eratosthenes optimization

I have applied some optimizations like storing only odd values and starting to mark off from square of the number. Can it be optimized further? ...
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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 ...
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parcel: a JSON parsing library in C

I've created a JSON parsing library in C, and would like some feedback on it (feel free to submit a pull request on GitHub). Any and all suggestions are acceptable, but I would prefer if reviews were ...
22k views

Smallest Multiple

I just recently learned about Project Euler and have started doing the problems on there. I cleared problem 1 and 2, had no idea how to do 3 and 4, and started to do 5. I've seen the post regarding ...
18k 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 ...