Coding Exercises

Re-create Ruby’s Max Method to Find the Largest Integer in an Array

December 24, 2016

6804

In this coding exercise, we walk through how to efficiently find the largest item in an array. Additionally, we examine how to implement performance tests to compare two different implementation options.

Summary

Implement a method that finds the largest integer in an array without using Ruby’s built-in max method. Additionally, ensure that the algorithm can work efficiently on large sets of data.

Exercise File

Code File

Exercise Description

Given the following array:

[1, 6, 3, 10, 5, 3]

Write a program that returns the largest integer in the array.

Example Output

Real World Usage

Finding the largest element in a collection is used in many algorithms. Additionally, you’ll discover that there are multiple solutions to this exercise, however, not all of the solutions are efficient. Working through this exercise should help you analyze the performance of each implementation option. And performance analysis is important in day to day development.

Solution

Can be found on the solutions branch on github.

7 COMMENTS

Zac Smith December 28, 2016 at 5:20 pm

This was a really great lesson! I learned a lot, and always feel that your videos provide useable skills and knowledge.

- Jordan Hudgens December 28, 2016 at 9:18 pm
  
  Thanks Zac, I’m glad that you found it helpful!
  
Douglas April 25, 2017 at 3:04 pm

Thanks for these lessons.
But you say new_max becomes 5?
How can it? 1 is not greater than 5 is it? Oops!

- Douglas April 25, 2017 at 3:20 pm
  
  I’m sorry. Not awake yet. Just looking at it didn’t make sense so I went and coded it for myself. I put a ‘p new_max’ in the loop. I’ve been using VSCode for all my Ruby and Python these days. So for my run of code note on the command line I did this bellow…
  if __FILE__ == $PROGRAM_NAME
  system ‘rspec 24.rb’
  end
  
  - Douglas April 25, 2017 at 5:35 pm
    
    A better way with a one liner.
    system ‘rspec 24.rb’ if __FILE__ == $PROGRAM_NAME
    
Joel January 11, 2018 at 3:35 pm

You mentioned you could improve the performance even more by caching. Could you explain how that works in this context?

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