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
148
questions
1
vote
1answer
45 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 ...
0
votes
0answers
32 views
7
votes
1answer
42 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
89 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
97 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
83 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
56 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 ...
2
votes
1answer
336 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
32 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
119 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
121 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 ...
0
votes
0answers
94 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
Best Time to Buy and Sell Stock
Say you have ...
3
votes
0answers
31 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
611 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 ...
4
votes
0answers
57 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
72 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
334 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
123 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
85 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
154 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
79 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
59 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
60 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
472 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
100 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
126 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 ...
6
votes
2answers
106 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
44 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 ...
15
votes
2answers
2k 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 ...
8
votes
1answer
63 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
56 views
3
votes
1answer
139 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
12k 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
117 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
60 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
117 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
335 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
120 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.
...
3
votes
0answers
160 views
Pandas data extraction task taking too much memory. How to optimize for memory usage?
I need to process some data (one of its columns contains a json/dict with params- I need to extract those params to individual columns of their own; catch- some rows have some parameters, others have ...
4
votes
1answer
2k views
Split a given number so that their sum adds to another given number
Task
You are given a string S containing only decimal digits ('0' through
'9') and a number N. Your task is to insert an arbitrary number
(including zero) of plus signs '+' into S in order to ...
6
votes
1answer
79 views
Build embedded XML based on string containment
I have a list of strings that represent a path. These are unique, unsorted values that look like this:
...
3
votes
2answers
101 views
Littlewood Polynomial Heatmap
The following Python program generates heat maps of the roots of Littlewood polynomials. It works fine with a small number of roots, however I tried to use 2^21 in the first loop and it ate up 12 ...
6
votes
2answers
109 views
Genetic Sequence Visualizer - Generating large images
Inspired by this reddit post, I have written a program that accepts a DNA sequence (in a FASTA file format) and generates a graphical representation.
HIV virus and Ebola virus
My program works like ...
11
votes
1answer
95 views
Python genetic sequence visualizer
I'm a beginner at python, and this is my first major project. Inspired by this reddit post, I wrote a program that accepts a DNA sequence (in a FASTA file format) and generates a graphical ...
5
votes
2answers
85 views
Transpose tab-delimited table in C
I have looked online for transposing programs, but have found that they have extreme RAM use for large tables. The RAM use is so extreme I can't run most jobs on my laptop. I also have a Perl ...
1
vote
1answer
3k views
Generating a word bigram co-occurrence matrix
I have written a method which is designed to calculate the word co-occurrence matrix in a corpus, such that element(i,j) is the number of times that word i follows word j in the corpus.
Here is my ...
8
votes
1answer
287 views
Calculating the Average Minimum Length of Random Numbers From 0 - 1 that Adds up to Greater Than 1
My Computer Science teacher gave us a task to calculate the average after one billion trials.
His exact assignment was this:
Consider generating a sequence of random numbers on the interval [0, 1) ...
4
votes
5answers
635 views
Find The Duplicates in two arrays
Find The Duplicates
Given two sorted arrays arr1 and arr2 of passport numbers, implement a function findDuplicates that returns an array of all passport numbers that are both in arr1 and arr2. Note ...
