Skip to content

Commit

Permalink
roman-numerals: sync (#808)
Browse files Browse the repository at this point in the history
* Sync the `roman-numerals` exercise's docs with the latest data.

* Sync the `roman-numerals` exercise's metadata with the latest data.
  • Loading branch information
ErikSchierboom committed Feb 15, 2024
1 parent efc3d60 commit 020de6e
Show file tree
Hide file tree
Showing 3 changed files with 68 additions and 38 deletions.
45 changes: 8 additions & 37 deletions exercises/practice/roman-numerals/.docs/instructions.md
Original file line number Diff line number Diff line change
@@ -1,41 +1,12 @@
# Instructions
# Introduction

Write a function to convert from normal numbers to Roman Numerals.
Your task is to convert a number from Arabic numerals to Roman numerals.

The Romans were a clever bunch.
They conquered most of Europe and ruled it for hundreds of years.
They invented concrete and straight roads and even bikinis.
One thing they never discovered though was the number zero.
This made writing and dating extensive histories of their exploits slightly more challenging, but the system of numbers they came up with is still in use today.
For example the BBC uses Roman numerals to date their programs.
For this exercise, we are only concerned about traditional Roman numerals, in which the largest number is MMMCMXCIX (or 3,999).

The Romans wrote numbers using letters - I, V, X, L, C, D, M.
(notice these letters have lots of straight lines and are hence easy to hack into stone tablets).
~~~~exercism/note
There are lots of different ways to convert between Arabic and Roman numerals.
We recommend taking a naive approach first to familiarise yourself with the concept of Roman numerals and then search for more efficient methods.
```text
1 => I
10 => X
7 => VII
```

The maximum number supported by this notation is 3,999.
(The Romans themselves didn't tend to go any higher)

Wikipedia says: Modern Roman numerals ... are written by expressing each digit separately starting with the left most digit and skipping any digit with a value of zero.

To see this in practice, consider the example of 1990.

In Roman numerals 1990 is MCMXC:

1000=M
900=CM
90=XC

2008 is written as MMVIII:

2000=MM
8=VIII

Learn more about [Roman numerals on Wikipedia][roman-numerals].

[roman-numerals]: https://wiki.imperivm-romanvm.com/wiki/Roman_Numerals
Make sure to check out our Deep Dive video at the end to explore the different approaches you can take!
~~~~
59 changes: 59 additions & 0 deletions exercises/practice/roman-numerals/.docs/introduction.md
Original file line number Diff line number Diff line change
@@ -0,0 +1,59 @@
# Description

Today, most people in the world use Arabic numerals (0–9).
But if you travelled back two thousand years, you'd find that most Europeans were using Roman numerals instead.

To write a Roman numeral we use the following Latin letters, each of which has a value:

| M | D | C | L | X | V | I |
| ---- | --- | --- | --- | --- | --- | --- |
| 1000 | 500 | 100 | 50 | 10 | 5 | 1 |

A Roman numeral is a sequence of these letters, and its value is the sum of the letters' values.
For example, `XVIII` has the value 18 (`10 + 5 + 1 + 1 + 1 = 18`).

There's one rule that makes things trickier though, and that's that **the same letter cannot be used more than three times in succession**.
That means that we can't express numbers such as 4 with the seemingly natural `IIII`.
Instead, for those numbers, we use a subtraction method between two letters.
So we think of `4` not as `1 + 1 + 1 + 1` but instead as `5 - 1`.
And slightly confusingly to our modern thinking, we write the smaller number first.
This applies only in the following cases: 4 (`IV`), 9 (`IX`), 40 (`XL`), 90 (`XC`), 400 (`CD`) and 900 (`CM`).

Order matters in Roman numerals!
Letters (and the special compounds above) must be ordered by decreasing value from left to right.

Here are some examples:

```text
105 => CV
---- => --
100 => C
+ 5 => V
```

```text
106 => CVI
---- => --
100 => C
+ 5 => V
+ 1 => I
```

```text
104 => CIV
---- => ---
100 => C
+ 4 => IV
```

And a final more complex example:

```text
1996 => MCMXCVI
----- => -------
1000 => M
+ 900 => CM
+ 90 => XC
+ 5 => V
+ 1 => I
```
2 changes: 1 addition & 1 deletion exercises/practice/roman-numerals/.meta/config.json
Original file line number Diff line number Diff line change
@@ -1,5 +1,5 @@
{
"blurb": "Write a function to convert from normal numbers to Roman Numerals.",
"blurb": "Convert modern Arabic numbers into Roman numerals.",
"authors": [
"ErikSchierboom"
],
Expand Down

0 comments on commit 020de6e

Please sign in to comment.