Optimization is the process of improving an existing program to make it work more efficiently or/and using less resources.

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Latency in creating configuration in apache commons configuration

I am planning to use Apache commons configuration (https://commons.apache.org/proper/commons-configuration/) to merge various configuration files. Since for me, the configuration file names are ...
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30 views

Are there compilers that implement immunity-aware programming techniques? [on hold]

Are there compilers with flags or directives to implement immunity-aware programming techniques such as function token passing data integrity verification and/or correction function parameter ...
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5answers
105 views

Use Exceptions for control flow in order to increase performance?

I add a lot of elements to a list of lists. If the list of lists my element should be saved to, does not exist yet, I handle this by catching an exception and adding a new list to my list of lists. ...
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19 views

How to calculate a lookup table index from comparing 3 variables treating equality as distinct cases

My code needs to use different lookup table values depending on the relative order of 3 simple input numeric variables a,b,c. If any of a,b,c are equal that's considered a distinct case. I'm looking ...
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5answers
362 views

Is it wise to rely on optimizations?

Should I write my code to be clear what I am doing and rely on the optimizer to clean up my code efficiency, or should I be obsessive about getting every last ounce of power out of my code? And how ...
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1answer
46 views

The optimal way to reschedule appointments

Let's say I have the following appointments: Appointment 1 = 1:00 Appointment 2 = 2:00 Appointment 3 = 3:00 Appointment 4 = 4:00 I need to reschedule all of these one hour later: Appointment 1 = ...
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5answers
264 views

My brute force solution is too slow, needed DP solution [closed]

Concise problem definition: given n and {a,b,c}; (1 ≤ n, a, b, c ≤ 4000); Constraint -> a*i + b*j + c*k==n (i,j,k>=0); Objective-> maximize(i,j,k) Examples: n=47 and a=7,b=5,c=8 -> ...
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1answer
135 views

Word ladder efficency problem

I have a problem dealing with word ladders. The problem is: given two words and a dictionary file, find the shortest word ladder between the two words. So if given the words cat and pot: cat -> ...
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1answer
78 views

Clairvoyance in caching - optimal strategies?

This question relates to the question here, but I'll generalise it so that you can answer effectively without reading all of that. Context: Imagine you had a large set of data greater than your ...
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11answers
2k views

How to deal with misconceptions about “premature optimization is the root of all evil”?

I've encountered many people who are dogmatically against anything which can be considered "optimization" in the general English-language sense of the word, and they very often quote verbatim the ...
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1answer
56 views

How to optimize a bloated entity that causes a huge query

I have an application that exposes a series of Web services. One of my entities has a bunch of one-to-many and many-to-many relations to other entities. My transactionality level is at DAO, and I'd ...
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4answers
92 views

How does a query execution plan affect query execution?

I have read some articles on SQL Server query optimization. The point I get is SQL Server generates a query execution plan for each stored procedure when it's executed for the first time. Those ...
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1answer
40 views

python snippet optimization explanation

I'm attempting optimize and figure out why for input n a function I wrote f(n) appears to never finish executing when n > 26. TL;DR I need to figure out how to find the complexity of various python ...
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57 views

Using counter or constant for parameter position

Suppose that I have the following Java code: int i = 0; PreparedStatement statement = con.prepareStatement("SELECT * FROM table " + "WHERE field1 = ?, field2 = ?, field3 = ?..."); ...
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1answer
83 views

Recieving errors without engaging in excessive communication when using sockets

I'm currently writing a program that communicates with a server over TCP sockets. I originally planned for the communication to include a message confirming successful communication at the end of ...
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3answers
135 views

Is denormalising a data structure essentially a code optimisation, to which the normal rules apply?

One of Bloch's Effective Java items 55: Optimize judiciously extends Jackson's rules on optimization: Rule no. 1: Don't optimise! Rule no. 2 (for experts): Don't optimise yet! Extra ...
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1answer
173 views

Approaching Particle Swarm Optimization with optimization problem, how to use PSO with it?

I am learning Particle Swarm Optimization. The problem is to find the pair of number whose sum is lowest. Lets say we have some numbers z1,z2,z3,z4 Number Value z1 -2 z2 -3 z3 3 ...
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81 views

Decision making algorithm

I'm currently solving an optimisation problem of my own design, just to experiment and learn a little something. Here's the concept: I have a user that starts at home. The objective of this user is ...
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1answer
138 views

Are there compilers which optimize the use of mathematical functions?

Today while programming I stumbled upon the following question - are there any compilers which optimize based on mathematical assumptions? For instance in cases like unsigned int i,b; (i,b not ...
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3answers
77 views

How to optimize iterable queries with external arguments

I will use C# here as an example, but my question is about any language. My question is from framework to compiler perspective (i.e the solution can be by implementing given idea inside compiler) ...
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2answers
157 views

Optimization problem where to start, what algorithms to use? [closed]

I have an optimization problem and I was wondering where to start from to be able resolve it. I think it can be solved with an NP-complete algorithm but I am not sure where to start from. The problem ...
2
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1answer
111 views

Improving sampling algorithm

I am having a bit of trouble designing a new feature at the moment. It is part of a resource management system. I was wondering if anyone has experience doing anything similar. I'll try to explain: ...
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3answers
114 views

What can qualify for potential tail call recursion (TCO) optimization or tail recursion elimination (TRE)

Short question is: what can qualify for potential tail call recursion optimization (TCO) or tail recursion elimination (TRE) if the compiler or interpreter supports it. The summary of this question ...
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79 views

Program to select N integers with constraints [closed]

I need to write a program which takes 4 inputs as follows N = The number of integers to be generated (10 < N < 10000) Start = The minimum value of the integers (100 < Start) End = The ...
2
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1answer
131 views

Maximizing Value and Volume, minimizing weight - Knapsack

Trying out a Knapsack variant where the rules are Any item you take must fit completely in the bag Usable metrics of the bag are length(l),width(w),height(h) and you can assume that if the products ...
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1answer
136 views

How to safely and cheaply delete a directory's contents that are constantly being deleted/overwritten

I'm coding something that will check a specific static location's directory, and if it exists, and a certain process has not run in n minutes, it deletes that directory's files and all sub-directory ...
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1answer
235 views

Combinatorial Optimization: Filling a Bag with Sand

I have an interesting "real-world" combinatorial optimization problem that I need to solve programmatically, however I have yet been able to whiteboard a good strategy. The task is similar to the ...
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1answer
100 views

Sorting an array based on another array's order, quickly [closed]

There are two arrays of maps. The first array contains maps of ID values in a specific order (but not necessarily either pure ASC or DESC ordering): // pseudo code first := [ {"id": 1}, ...
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1answer
118 views

Optimization: How much time saved is considered worth it? [closed]

I was reading up about branch predictions and cache misses, and have decided to read what every programmer should know about memory. But I'm not sure how much low level knowledge do I need to have to ...
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1answer
70 views

Multiple variable assignment vs HashTable lookup

I'm writing a CUIT ( Coded UI Test ) and I'm replacing variables with data fetched from a csv. Example: this.UIMap.IDBParams.UITboxFsEditText = TestContext.DataRow["num_fs"].ToString(); ...
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1answer
119 views

storing single character value use string or int C# [closed]

While storing single character value for the purpose of status, gender, delete_flag etc. which is better data type string or int. Suppose :: status = A/I or status = 1/0 gender = M/F or gender = 1/0 ...
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2answers
191 views

Do nested conditionals have a significant performance impact? [duplicate]

This is a question that lives in my mind from a long time. Does the use of multiple nested conditional statements impact the performance of a taken code? So far I know that programmers have created a ...
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147 views

How to distribute a number of elements in a bucket so that it is within a range?

I have 50 elements n1, n2, n3, ... , n50 and a limited number of buckets, say 5 buckets and each bucket can hold a range from, say 100 to 150 only (which is nothing but the sum of the elements in that ...
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42 views

Cost of cache coherency/sharing data across multiple cores?

If I have two CPU cores, one is writing a particular cache line and the other core wishes to Read Write the same cache line, what are the costs (in cycles) for doing so? I am a little unsure ...
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3answers
79 views

Premature memoization on obvious cases

In the code below there will be several instances of MainClass. class MainClass(object): def f(self, x): # expensive operations. # ... return 'something' Each instance ...
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3answers
3k views

Linking two or more different programming languages

I would like to ask how optimizer software written in C/C++ can be linked to simulator software written in FORTRAN or any other language. I have copied the section of journal article of Singh and ...
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2answers
85 views

How do you avoid dominant solutions in multi-objective simulated annealing?

Imagine an RPG game were you can cary N items, and you want to maximise your damage, attack speed and armour, given a set of items. I implemented simulated annealing where a permutation simply ...
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56 views

Microcontroller oLED Display Buffering Optimizations or Alternatives For Speed?

I'm developing a UI/Layout for a 128 x 64 oLED Monochrome Pixel Display. I've got a small netMF microcontroller driving the display via SPI at 40mhz. I'm using some basic methods, like these here, to ...
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5answers
326 views

Can a pimpl variation be implemented without any performance penalty?

One of the issues of pimpl is the performance penalty of using it (additional memory allocation, non-contiguous data members, additional indirections, etc..). I would like to propose a variation on ...
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1answer
96 views

Optimizing instant notifications

Scenario To deliver instant notifications to the client, I'm sending an AJAX request to a PHP page that checks if there are new notifications: if there are, it outputs them, otherwise it sleeps for ...
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1answer
112 views

Can fast, optimized server calls collapse a server?

I've followed a series of optimizations to make our APIs faster. We microoptimized a lot of PHP code to faster, native methods, we unsed variables where they were not being used anymore, and basically ...
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3answers
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My algorithm that extracts the largest box that can be made from smaller boxes, is too slow

Imagine a cube based world (such as Minecraft, Trove, or Cube World) where everything is made up of identically sized cubes and all the cubes are of the same kind. The goal is to represent the world ...
3
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2answers
97 views

Reducing a sequence of array modification operations (insert, sort, replace, remove)

Given a plain array of values, e.g. ["Apple", "Orange", "Banana", "Strawberry"] and a list of operations from the set of [insert, delete, sort and replace], e.g. [ {cmd: "insert", index: 2, ...
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3answers
345 views

Work out which parcel deliveries we ship ourselves and which we outsource

Firstly, I hope I'm asking this in the right place. I work for a large online retailer in UK. We ship approaching 2000 orders each day and are growing very quickly. We currently use multiple delivery ...
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45 views

Approaches to combinatorial optimization problem

Problem I have the following combinatorial optimization problem: A set of applications need to be distributed among a set of nodes. Each node has a capacity and each application has a required ...
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0answers
26 views

Feasible solution on the constructions phase of GRASP

I am learning about the GRASP (Greedy Randomized Adaptive Search) meta-heuristics. From what I understood, GRASP is based on two main phases. The first one: Construct a initial solution based on ...
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1answer
77 views

Is serving a single document from a server to a browser slower than serving multiple documents?

I was looking into how to optimize web pages and the biggest way (code-wise) to optimize a website is to reduce the number of requests a browser has to make to your web server to get the full page. ...
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2answers
191 views

Algorithm for comparing hundreds of similar, but not identical documents

I have seen similar questions about text comparison, but none on such a large scale. I have a client with two sets of recordings of speeches, 250 and 550 recordings each. Each of the recordings in ...
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0answers
55 views

Optimizing trigram look ups with wildcards

I am working on creating a spell-checking service for Android (note: this is a platform- and language-neutral question) for Asturian, a minority Romance language. We're using hunspell as the base but ...
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126 views

Does loop unrolling on a JIT platfrom (.NET or JVM) provide any benefit

I know in C, you can use loop unrolling (unwinding) to help reduce branching in your code but at the expense of program size. That seems to work when you compile to a target machine, however, does it ...