Questions tagged [memory-optimization]
Memory Optimization is a subset of Optimization: it is the goal of reducing the memory consumption (the amount of memory used during compile or run time) of your program or of a specific algorithm
158
questions
7
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2answers
438 views
hexdump(): A memory layout utility to help debugging / understanding / optimising of C++ memory model
EDIT: Refer this answer for improved solution with incorporated feedback and extended functionality. eg Automatically hexdump both parts of a stack/heap obj like <...
2
votes
1answer
47 views
Further Optimizing a Segmented Sieve of Eratosthenes
I've implemented a Segmented Sieve of Eratosthenes that assumes each segment is about length \$ \sqrt{N}\$ for some upper limit \$N\$.
I further optimized the function by skipping all the evens when ...
-1
votes
2answers
126 views
TrainSet Practice Problem from CodeChef
A dataset consisting of N items. Each item is a pair of a word and a boolean denoting whether the given word is a spam word or not.
There shouldn't be a word included in the training set that's ...
1
vote
2answers
56 views
Decrypt multiple 10Mb files with defined password
One operation of my Android project is to decrypt one file (chosen in a set of ~30 files for pagination1) of ~10 Mb each and I do this with the following:
...
2
votes
1answer
43 views
Optimizing a TFxIDF vectorization - Python 3.x [closed]
I am attempting to train many classifiers to test their performance with classifying tweets as being from a political bot, or not (a binary 0 or 1 classifier).
My ...
4
votes
1answer
117 views
C# handling of images - is this best for memory usage?
I am working with a system that needs to consume product images uploaded by employees and resize them / add white padding to the sides to create square images to be consumed by our e-commerce site. I'...
2
votes
0answers
111 views
Split a string into valid words
I am trying to solve this LeetCode question:
Given a non-empty string s and a dictionary wordDict containing a list
of non-empty words, add spaces in s to construct a sentence where each
word ...
5
votes
1answer
63 views
Bank account balance program
Would my code be considered fairly optimal and efficient? If not, where can I look to improve the code? The program works just fine.
Would this method scale well if the dictionary containing the ...
4
votes
1answer
79 views
Incremental Sieve of Eratosthenes Generator
So I was fiddling around with the Euler challenges. One of the things they mentioned in their discussions of the solutions is the Sieve of Eratosthenes and that you can only use it when you know an ...
4
votes
1answer
46 views
Optimizing away log function calls depending on global log level
I am a member of a university team designing a nanosatellite.
We decided to implement our own (more lite) logging library to use, instead of, say, Google's glog, <...
2
votes
2answers
87 views
Generate a large block diagonal covariance matrix with exponential decay
I am implementing Kalman filtering in R. Part of the problem involves generating a really huge error covariance block-diagonal matrix (dim: 18000 rows x 18000 columns = 324,000,000 entries). We denote ...
1
vote
1answer
154 views
8
votes
1answer
168 views
Custom malloc implementation
I have a malloc() implementation that relies purely on mmap. I'm fairly sure that it doesn't overwrite any of the internal ...
2
votes
2answers
93 views
Generating recursive class instances from an array of splitted values by dashes (as a folder tree)
Well, I'm trying to generate the following:
Input:
...
6
votes
2answers
103 views
Program for activity selection exceeds time limit
I've been trying to solve this problem for some while and the solution I have come up with exceeds the lime limit by 1-3 ms and 2 out of 10 tests get a memory issue error. Why is that? This is the ...
2
votes
1answer
595 views
Python script for sorting a huge log file based on timestamps
I want to write a python script to sort a huge file, say 2 GB in size, which contains logs in the following format -
...
1
vote
1answer
63 views
Python's eval command in Arduino
I have made an equivalent of Python's "eval" command in Arduino (which in itself is quite a feat) but the part that decodes the output of it is not small enough to fit in another 30 functions since ...
3
votes
1answer
2k views
ASP.NET Core Request / Response logging middleware
I am looking for feedbacks about my ASP.NET Core Request / Response logging middleware, in particular in ways to lower the memory footprint and string allocations:
...
2
votes
0answers
41 views
Initializing Reinforcement Learning Q-Table State Space-Python
The code below is a "World" class method that initializes a Q-Table for use in the SARSA and Q-Learning algorithms.
Without going into too much detail, the world has "Pickups" and "Dropoffs" that can ...
6
votes
1answer
136 views
Matrix class with space-optimized triangular (lower and upper) variants
I've written a class for square numerical matrices (of doubles, in this case), in C++11. Since I intend to use this class later ...
3
votes
3answers
133 views
Computing average duration per user from a large CSV file that doesn't fit in memory
We have a large log file which stores user interactions with an application. The entries in the log file follow the following schema: {userId, timestamp, actionType} where actionType is one of two ...
3
votes
0answers
246 views
Kadane's algorithms to leetcode “121 Best Time to Buy and Sell Stock”
I employed the conventional Kadane's algorithms to solve a maximum subarray problem in leetcode Best Time to Buy and Sell Stock - LeetCode
Description
Best Time to Buy and Sell Stock
...
4
votes
0answers
40 views
Two solutions to leetcode 127.wordLadder
I am working on Word Ladder - LeetCode
Given two words (beginWord and endWord), and a dictionary's word list, find the length of shortest transformation sequence from beginWord to endWord, such ...
6
votes
2answers
1k views
In place solution to remove duplicates from a sorted list
I am working on the problem removeDuplicatesFromSortedList
Given a sorted array nums, remove the duplicates in-place such that each element appear only once and ...
6
votes
1answer
105 views
Ternary Search Tree / N-Gram Model in Python
I implemented a word n-gram model using a character ternary search tree. It is intended to be passed a generator that yields a long sequence of words (from a corpus) and its requirements are that it
...
2
votes
1answer
74 views
Writing a more Pythonic solution to the min triangle path
The problem I'm referring to is available here. In quick summary, the problem gives a list of lists such as [[2],[3,4],[6,5,7],[4,1,8,3]] and we must find the minimum path sum: 2 + 3 + 5 + 1 = 11. I ...
15
votes
3answers
370 views
Traversing an infinite graph using Dijkstra's algorithm to maximize cookie production speed
Imagine the following situation:
It is the year 20XX. You are a prodigious baker, capable of baking cookies at an astonishing rate of 1 cookie per second. Your archnemesis, an equally excellent baker,...
3
votes
1answer
370 views
json2CSV fails because of lack of RAM memory
I run this code on my Heroku Node.js server in order to get CSV for few hundred rows, but it fails with R14 - Memory Quota Exceeded.
It worked fine when there were ...
1
vote
0answers
118 views
Golang message bus for a game engine
I wrote a memory bus struct in golang to allow systems to interact with each other without knowing anything about the receiver.
This is for a game engine. I know it's not good to write games in ...
1
vote
4answers
194 views
Read a palindrome of unknown length
I have a task to write the function:
int read_palindrome(); // input comes from stdin
which will read one line from standard input and returns 1 if the line is a ...
1
vote
2answers
54 views
Check whether an array can be the result of merging two smaller arrays, maintaining order
I'm prepping for a tech interview coming up and trying to have a better understanding of what I should look out for in writing code. Also, feel free to correct the terminology that I use as I want to ...
2
votes
1answer
80 views
Grouping items in a list into inner lists
I have a function that looks up in a list the elements which share same values in order to group them.
As a fast summary, this should be the input/output:
[A, A'...
3
votes
0answers
60 views
Minimization problem solving and its step limits
I am trying to solve the following minimization problem:
$$
\min\lvert\lvert{x}\rvert\rvert_1 + \beta\lvert\lvert{x}\rvert\rvert^2_2 s.t. \sum_{m = 1}^M (y - \lvert{c}^{H} . x\rvert^2)^2 \le \epsilon
...
1
vote
1answer
66 views
Header-only vector implementation in C
I tried to make a generic, header-only vector thingy I can use in other projects in the future. I omitted documentation comments because it's already quite long.
...
8
votes
2answers
550 views
Sparse 3D binning/histogram function
This is a function written in Python I wrote to process galaxy catalogs for cosmology research, however it is more generally applicable than just my pipeline.
The goal is to take a Python list of ...
2
votes
2answers
108 views
Genetic Algorithm - heavy memory usage
I have implemented two pieces of code as part of an Evolutionary Algorithm study: Particle Swarm Optimisation (PSO) and Genetic Algorithm (GA). Both are designed to find an optimal solution to a ...
1
vote
0answers
15 views
Swapping variable length strings asynchronously with connected microcontroller (Byte-banging)
I have an AT89S52 and an AT89C4051 microcontroller (both in the 8052 family) in which the bit lines of the data bus, one control pin and one status pin are connected together. In code, the data bus is ...
3
votes
2answers
127 views
Simple recursive transformation solution in Python
This simple Python code I wrote for a problem asked during an interview. The problem statement is:
Given a tuple (a, b), transform this into (c, d) by applying any of the two below operations ...
7
votes
2answers
128 views
Prime number segmented sieve
I tried to solve the SPOJ prime number problem below. The code produced correct results, but Time limit exceeded and also memory need around 970M which is not efficient(?)
How can I optimize this ...
1
vote
0answers
65 views
Applying a filter to a large array with elements that are not regularly spaced
I need to apply a Gaussian filter to a 2D numpy array where the distance between adjacent array elements depends on the row of the array. (Specifically, the data are evenly spaced in latitude and ...
18
votes
2answers
4k views
Intersection over Union for rotated rectangles
Problem Statement
I am trying to find the intersection over union (IoU) metric for one to several rotated rectangles compared to many different rotated rectangles. Here are some images to help ...
9
votes
1answer
66 views
Search father (x) of the number D(x) and measure time and memory consumed
We define function D(x) as following:
D(x) = x + sum of digits of x
+ sum of prime factors of x then call x the father of D(x)
Write a program that gets input ...
1
vote
1answer
71 views
3
votes
1answer
165 views
Optimizations of C Code - Bilateral Filter
I'm working on a nice approximation for the Bilateral Filter.
I have a working code which runs pretty fast yet still I think much can be improved.
The code (C Code,...
5
votes
1answer
20k views
Count duplicates in a JavaScript array
This is actually a hackerrank interview question I have already solved but I need guidance on how to optimize it for the
Time
Space
Given an array of integers, your task is to count the number of ...
2
votes
1answer
120 views
Find the nearest coin to be collected in a game
I am creating a simple bot that collects coins in-game. The code runs under a game-loop so there are 60 ticks p/s
Here is the function that I use to check for the nearest coin (Game object) to be ...
2
votes
2answers
61 views
Eigenvector calculation involving three matrices
Code performs well for small matrices, but gives memory error for large matrices of size 63000x93000, even when I am using server with memory of 64GB, space 100GB, swap 40GB.
...
1
vote
2answers
156 views
Codility's BinaryGap: Hardware-aware answer [closed]
This is a well-known question, which some others have posted about on this site.
Here's my first shot following a state machine approach:
...
4
votes
1answer
647 views
Huffman Coding library implemented in C
I have written a small library for C that implements the Huffman coding algorithm as outlined in David Huffman's paper on Minimum-Redundancy Codes, and a small test program to implement it. The ...
8
votes
2answers
138 views
Maximize a traveling employee's vacation over k weeks
I have following problem statement
A lazy employee works at a multi-national corporation with N offices
spread across the globe.
They want to work as few days over k weeks as possible.
...
