Roman numeral converter solution

Contributors
1

Hello @all, this is my solution, with comments. I think could be good for newbies because there's not too much logic and it's a step by step process.
I hope i posted in the right place. 

function convertToRoman(num) {
/* convert the number to a string and split it in elements that will be stored in splittedNum array */
let splittedNum = num.toString().split("");

// create arrays for roman numbers entities
let romanMig = [], romanCents = [], romanDecine = [], romanUnits = [];
romanUnits = [ "I", "II", "III", "IV", "V", "VI", "VII", "VIII", "IX", "X"];
romanDecine = ["X", "XX", "XXX", "XL", "L", "LX", "LXX", "LXXX", "XC", "C" ]
romanCents = ["C", "CC", "CCC", "CD", "D", "DC", "DCC", "DCCC", "CM", "M"];
romanMig = ["M", "MM", "MMM", "MMMM", "MMMMM", "MMMMMM", "MMMMMMM", "MMMMMMMM","MMMMMMMMM", "MMMMMMMMMM" ];

/* the functions below first extracts the value of the unit (dec , cent, migliaia) from the relative index of the splitted number (array.length - 1 for units, - 2 for dec, - 3 for cents, - 4 for migliaia). 
For example we extract the unit "6" from  "36".
Then we use the number 6 to extract the corresponding roman number (VI) from the array romanUnits []. 
Using 6 as index-1 ( because the array index starts from 0) in the array romanUnits we got romanUnits[5]  and we etract the corresponding element at index 5 > that is VI
In fact index 0 = "I", index 1 = "II",  index 2 = "III", index 3 =  "IV", index 4 = "V", index 5 = "VI", etc...).
Same approach with decine (position in the number is at array.length -2 (in the example with the number 36 we extract  3 from the splittedNum ["3", "6"]  ), 
Then set the code for doing the same with cent (position at -3) and migliaia (position at -4) in case of bigger number provided to the functions.
*/

const findRomanUnit = arr => arr[splittedNum[(splittedNum.length - 1)] -1 ];
const findRomanDecina = arr => arr[splittedNum[(splittedNum.length - 2)] - 1];
const findRomanCents = arr => arr[splittedNum[(splittedNum.length - 3)] - 1]
const findRomanMig = arr => arr[splittedNum[(splittedNum.length - 4)]- 1];

// synthetize the above code 
const migliaia = findRomanMig(romanMig);
const cen = findRomanCents(romanCents);
const dec = findRomanDecina(romanDecine);
const un = findRomanUnit(romanUnits);

// we build our array model for the roman number, based on position of the values
let romanNum = [migliaia, cen, dec, un];

/* now we create a function to eliminate elements that throw undefined from our array, for example numbers like 2014, having a zero inside, can throw undefined for the cents
*/

function eliminaUndef (arr) {
    let newArr = arr.filter(el => el !== undefined);
    return newArr.join("").toString();      
}

let result = eliminaUndef(romanNum);
return result;

   
}

 convertToRoman(36);

Hope it helps, Bye

2

as it seems you want to contribute to the guide I am moving your post to a new topic

3

Hello there.

Thank you, for your contribution. For future contributions, please wrap your solution within :

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4

Gotcha (i think) Thank You : )

5

I like your solution. It makes sense to me, and I think it’s better than what I managed to come up with.

6

Silly question, but why does it say I created this topic when it was created by someone else?

image
image704×211 12.6 KB

7

I am unsure, but could be one of the following:

  • This topic was created by a moderator splitting a reply from another topic. If you created the original topic, this could be residual.
  • A previous post you created and read caused that state. Now, when you came here, the state did not update correctly.

Thanks, for pointing it out.

8

Hello,
Thanks for replying.
As You can see in the first answer, right after the first post of the topic, ieahleen, who is a moderator, replied:

“as it seems you want to contribute to the guide I am moving your post to a new topic”

In fact, originally i posted my solution in the wrong place: in someone else’s topic about the same challenge.
So ieahleen kindly moved my post to a new topic.
Thank You,
have a nice :sunny: day.

9

thank you
Glad if You share your solution too.