||3 years ago|
|README.md||3 years ago|
|prime_factors.rb||3 years ago|
|prime_factors_test.rb||3 years ago|
Compute the prime factors of a given natural number.
A prime number is only evenly divisible by itself and 1.
Note that 1 is not a prime number.
What are the prime factors of 60?
- Our first divisor is 2. 2 goes into 60, leaving 30.
- 2 goes into 30, leaving 15.
- 2 doesn't go cleanly into 15. So let's move on to our next divisor, 3.
- 3 goes cleanly into 15, leaving 5.
- 3 does not go cleanly into 5. The next possible factor is 4.
- 4 does not go cleanly into 5. The next possible factor is 5.
- 5 does go cleanly into 5.
- We're left only with 1, so now, we're done.
Our successful divisors in that computation represent the list of prime factors of 60: 2, 2, 3, and 5.
You can check this yourself:
- 2 * 2 * 3 * 5
- = 4 * 15
- = 60
For installation and learning resources, refer to the exercism help page.
For running the tests provided, you will need the Minitest gem. Open a terminal window and run the following command to install minitest:
gem install minitest
If you would like color output, you can
require 'minitest/pride' in
the test file, or note the alternative instruction, below, for running
the test file.
Run the tests from the exercise directory using the following command:
To include color from the command line:
ruby -r minitest/pride prime_factors_test.rb
The Prime Factors Kata by Uncle Bob http://butunclebob.com/ArticleS.UncleBob.ThePrimeFactorsKata
Submitting Incomplete Solutions
It's possible to submit an incomplete solution so you can see how others have completed the exercise.