iwc

iwc

A Common-Sense Guide to Data Structures and Algorithms, Second Edition: number_of_paths implementations are not equivalent (pg. 176/177)

There are two provided implementations for the number_of_paths function. The ‘hardcoded’ version is correct, but the simplified version is not.

pg. 176

def number_of_paths(n):
  return 0 if n <= 0
  return 1 if n == 1
  return 2 if n == 2
  return 4 if n == 3
  return number_of_paths(n - 1) + number_of_paths(n - 2) + number_of_paths(n - 3)
end

pg. 177

def number_of_paths(n):
  return 0 if n < 0
  return 1 if n == 1 || n == 0
  return number_of_paths(n - 1) + number_of_paths(n - 2) + number_of_paths(n - 3)
end

Page 177’s implementation returns 1 instead of 0 for number_of_paths(0).

First Post!

jaywengrow

jaywengrow

Author of A Common-Sense Guide to Data Structures and Algorithms

Thanks for submitting this. While you are correct that the two methods are not identical in this regard, that is by design. I explain there in the text between the two versions that in the simplified version, we are “rigging” the base case of 0 to return 1 for the very sake of simplifying the code. I hope that helps!

Where Next?

Popular Pragmatic Bookshelf topics Top

sdmoralesma
Title: Web Development with Clojure, Third Edition - migrations/create not working: p159 When I execute the command: user=&gt; (create-...
New
mikecargal
Title: Hands-on Rust: question about get_component (page 295) (feel free to respond. “You dug you’re own hole… good luck”) I have somet...
New
rmurray10127
Title: Intuitive Python: docker run… denied error (page 2) Attempted to run the docker command in both CLI and Powershell PS C:\Users\r...
New
adamwoolhether
When trying to generate the protobuf .go file, I receive this error: Unknown flag: --go_opt libprotoc 3.12.3 MacOS 11.3.1 Googling ...
New
jskubick
I’m running Android Studio “Arctic Fox” 2020.3.1 Patch 2, and I’m embarrassed to admit that I only made it to page 8 before running into ...
New
jskubick
I’m under the impression that when the reader gets to page 136 (“View Data with the Database Inspector”), the code SHOULD be able to buil...
New
brunogirin
When I run the coverage example to report on missing lines, I get: pytest --cov=cards --report=term-missing ch7 ERROR: usage: pytest [op...
New
akraut
The markup used to display the uploaded image results in a Phoenix.LiveView.HTMLTokenizer.ParseError error. lib/pento_web/live/product_l...
New
andreheijstek
After running /bin/setup, the first error was: The foreman' command exists in these Ruby versions: That was easy to fix: gem install fore...
New
a.zampa
@mfazio23 I’m following the indications of the book and arriver ad chapter 10, but the app cannot be compiled due to an error in the Bas...
New

Other popular topics Top

ohm
Which, if any, games do you play? On what platform? I just bought (and completed) Minecraft Dungeons for my Nintendo Switch. Other than ...
New
siddhant3030
I’m thinking of buying a monitor that I can rotate to use as a vertical monitor? Also, I want to know if someone is using it for program...
New
AstonJ
Thanks to @foxtrottwist’s and @Tomas’s posts in this thread: Poll: Which code editor do you use? I bought Onivim! :nerd_face: https://on...
New
AstonJ
In case anyone else is wondering why Ruby 3 doesn’t show when you do asdf list-all ruby :man_facepalming: do this first: asdf plugin-upd...
New
Help
I am trying to crate a game for the Nintendo switch, I wanted to use Java as I am comfortable with that programming language. Can you use...
New
AstonJ
If you want a quick and easy way to block any website on your Mac using Little Snitch simply… File &gt; New Rule: And select Deny, O...
New
PragmaticBookshelf
Author Spotlight: VM Brasseur @vmbrasseur We have a treat for you today! We turn the spotlight onto Open Source as we sit down with V...
New
PragmaticBookshelf
Develop, deploy, and debug BEAM applications using BEAMOps: a new paradigm that focuses on scalability, fault tolerance, and owning each ...
New
AstonJ
This is a very quick guide, you just need to: Download LM Studio: https://lmstudio.ai/ Click on search Type DeepSeek, then select the o...
New
AstonJ
Curious what kind of results others are getting, I think actually prefer the 7B model to the 32B model, not only is it faster but the qua...
New

Sub Categories: