Learning Resources>Coding Challenges

Tree random element

#coding-challenge#trees#random
BorjaEst

BorjaEst

Trees (specially gb_trees) are a very efficient/fast tool to store Key-Value. However, depending on the program it’s usage cat get a bit more complicated.

Here goes my challenge.
What would be the most efficient way to get a random element and it’s path from a gb_tree?

3 comments
#coding-challenge#trees#random
1053 3

First Post!

al2o3cr

al2o3cr

:gb_trees.iterator/1 plus a reservoir sampling algorithm?

0
Post #1

Last Post!

BorjaEst

BorjaEst OP

So after thinking about it, my solution would be something like this:

iex(1)> tree = :gb_tree.example() #Any f that returns a tree
{3, {:a, 1, nil, {:b, 2, nil, {:c, 3, nil, nil}}}}
iex(2)> n = :rand.uniform(:gb_trees.size(tree))
2
iex(11)> iter = :gb_trees.iterator(tree) 
[{:a, 1, nil, {:b, 2, nil, {:c, 3, nil, nil}}}]
iex(14)> {k,v,_}=Enum.reduce(1..n, {:nil,:nil,:gb_trees.iterator(tree)}, fn _, {_,_,i} -> :gb_trees.next(i) end)
{:b, 2, [{:c, 3, nil, nil}]}

However I am thinking, now gb_trees are not used any longer as we do have maps.

0
Post #3

Where Next? Top

View thread on forum (has 3 replies!)
coding-challenge
trees
random
Home Learning Resources>Coding Challenges
0 961 3
Last post
REPLY VIEW THREAD WITH 3 POSTS

Trending in Challenges Top

Other Trending Topics Top

JesseHerrick
News>Announcing

Dexter - A fast, full-featured Elixir LSP optimized for large codebases
Hey, I’m Jesse and I’m the main contributor behind Dexter, a full-featured, lightning-fast Elixir LSP optimized for large codebases. It s...
#library#lsp#dexter
184 6895 63
New
mudasobwa
Chat & Discussions>Discussions

Cure - a new language compiled to BEAM
I am happy to introduce the very α version of the new programming language compiled to BEAM. Welcome Cure. It has literally three kille...
#static-types#type-checking#types#fsm
168 5507 69
New
marciok
News>Announcing

Gust - A task orchestration system built in Elixir
Hi there! We created Gust: A task orchestrator inspired by Airflow. For those who have never heard about Aiflow, it’s a Python-based wor...
/phoenix/oban#library#workflow#background_job#reactor
111 4469 40
New
mhanberg
Chat & Discussions>Discussions

Expert LSP is now available!
Hi everyone! The first release candidate for the Expert language server project is now available! We’ve published a press release detai...
#lsp#expert
220 4348 38
New
jimsynz
News>Announcing

Beam Bots - Resilient Robotics on the BEAM
Beam Bots (or just BB for short) is a framework for building fault-tolerant robotics applications in Elixir using familiar OTP patterns. ...
/beam-bots#library#robotics#bb
119 2916 28
New
Dmk
News>Announcing

Xamal - Deploy Elixir releases to bare metal servers via SSH
Xamal is a deployment tool for Elixir apps that deploys native releases to bare metal servers over SSH. It’s a port of GitHub - basecamp/...
#library#deployment#deploy#deployments#xamal
75 2512 33
New
Back to top

Learning Resources>Coding Challenges

Resources Challenges ❯

Latest on Elixir Forum

Elixir Forum ❯

Sponsor Spotlight

Dashbit

Build Elixir applications with speed and confidence.

Our Sponsors

EEF

Supporting innovation across the BEAM ecosystem.

Coders51

We build reliable cloud platforms for business-critical systems.

AppSignal

Catch errors, track performance, monitor hosts and more.

Honeybadger

Error tracking, logs, uptime, and Just Enough APM. Built for developers.

Code Sync

Elixir, Erlang & BEAM conferences from Code Sync - join us in 2026!

Pragmatic Bookshelf

Practical resources that improve the lives of professional developers.

Defacto

Bringing learning, work and compliance together since 1987.

Potions

The deployment platform built for Elixir: PaaS ease, VPS control.

Software Mansion

The team behind Membrane, Popcorn, LiveDebugger. Available for hire.

Pragmatic Studio

Courses that'll move you from confusion to "Aha, now I get it!"

View all our sponsors ❯

Categories:

Sub Categories:

Forums

Popular Tags

Our Sponsors

EEF

Supporting innovation across the BEAM ecosystem.

Coders51

We build reliable cloud platforms for business-critical systems.

AppSignal

Catch errors, track performance, monitor hosts and more.

Honeybadger

Error tracking, logs, uptime, and Just Enough APM. Built for developers.

Code Sync

Elixir, Erlang & BEAM conferences from Code Sync - join us in 2026!

Pragmatic Bookshelf

Practical resources that improve the lives of professional developers.

Defacto

Bringing learning, work and compliance together since 1987.

Potions

The deployment platform built for Elixir: PaaS ease, VPS control.

Software Mansion

The team behind Membrane, Popcorn, LiveDebugger. Available for hire.

Pragmatic Studio

Courses that'll move you from confusion to "Aha, now I get it!"

View all our sponsors ❯

We're in Beta

About us Mission Statement

Options

Thread Display Mode




Thread Preview

Skip Thread Previews