55 lines
2.4 KiB
Markdown
55 lines
2.4 KiB
Markdown
# Raindrops
|
|
|
|
Write a program that converts a number to a string, the contents of which depends on the number's prime factors.
|
|
|
|
- If the number contains 3 as a prime factor, output 'Pling'.
|
|
- If the number contains 5 as a prime factor, output 'Plang'.
|
|
- If the number contains 7 as a prime factor, output 'Plong'.
|
|
- If the number does not contain 3, 5, or 7 as a prime factor,
|
|
just pass the number's digits straight through.
|
|
|
|
## Examples
|
|
|
|
- 28's prime-factorization is 2, 2, 7.
|
|
- In raindrop-speak, this would be a simple "Plong".
|
|
- 1755 prime-factorization is 3, 3, 3, 5, 13.
|
|
- In raindrop-speak, this would be a "PlingPlang".
|
|
- The prime factors of 34 are 2 and 17.
|
|
- Raindrop-speak doesn't know what to make of that,
|
|
so it just goes with the straightforward "34".
|
|
|
|
## Getting Started
|
|
|
|
Make sure you have read the [getting started with C++](http://help.exercism.io/getting-started-with-cpp.html)
|
|
page on the [exercism help site](http://help.exercism.io/). This covers
|
|
the basic information on setting up the development environment expected
|
|
by the exercises.
|
|
|
|
## Passing the Tests
|
|
|
|
Get the first test compiling, linking and passing by following the [three
|
|
rules of test-driven development](http://butunclebob.com/ArticleS.UncleBob.TheThreeRulesOfTdd).
|
|
Create just enough structure by declaring namespaces, functions, classes,
|
|
etc., to satisfy any compiler errors and get the test to fail. Then write
|
|
just enough code to get the test to pass. Once you've done that,
|
|
uncomment the next test by moving the following line past the next test.
|
|
|
|
```C++
|
|
#if defined(EXERCISM_RUN_ALL_TESTS)
|
|
```
|
|
|
|
This may result in compile errors as new constructs may be invoked that
|
|
you haven't yet declared or defined. Again, fix the compile errors minimally
|
|
to get a failing test, then change the code minimally to pass the test,
|
|
refactor your implementation for readability and expressiveness and then
|
|
go on to the next test.
|
|
|
|
Try to use standard C++11 facilities in preference to writing your own
|
|
low-level algorithms or facilities by hand. [CppReference](http://en.cppreference.com/)
|
|
is a wiki reference to the C++ language and standard library. If you
|
|
are new to C++, but have programmed in C, beware of
|
|
[C traps and pitfalls](http://www.slideshare.net/LegalizeAdulthood/c-traps-and-pitfalls-for-c-programmers).
|
|
|
|
## Source
|
|
|
|
A variation on a famous interview question intended to weed out potential candidates. [view source](http://jumpstartlab.com)
|