2018-10-04 13:37:37 +00:00
|
|
|
---
|
|
|
|
id: 5900f36f1000cf542c50fe82
|
|
|
|
challengeType: 5
|
|
|
|
title: 'Problem 3: Largest prime factor'
|
|
|
|
---
|
|
|
|
|
|
|
|
## Description
|
|
|
|
<section id='description'>
|
|
|
|
The prime factors of 13195 are 5, 7, 13 and 29.
|
|
|
|
What is the largest prime factor of the given <code>number</code>?
|
|
|
|
</section>
|
|
|
|
|
|
|
|
## Instructions
|
|
|
|
<section id='instructions'>
|
|
|
|
|
|
|
|
</section>
|
|
|
|
|
|
|
|
## Tests
|
|
|
|
<section id='tests'>
|
|
|
|
|
|
|
|
```yml
|
|
|
|
tests:
|
|
|
|
- text: <code>largestPrimeFactor(2)</code> should return 2.
|
2018-10-08 00:01:53 +00:00
|
|
|
testString: 'assert.strictEqual(largestPrimeFactor(2), 2, "<code>largestPrimeFactor(2)</code> should return 2.");'
|
2018-10-04 13:37:37 +00:00
|
|
|
- text: <code>largestPrimeFactor(3)</code> should return 3.
|
2018-10-08 00:01:53 +00:00
|
|
|
testString: 'assert.strictEqual(largestPrimeFactor(3), 3, "<code>largestPrimeFactor(3)</code> should return 3.");'
|
2018-10-04 13:37:37 +00:00
|
|
|
- text: <code>largestPrimeFactor(5)</code> should return 5.
|
2018-10-08 00:01:53 +00:00
|
|
|
testString: 'assert.strictEqual(largestPrimeFactor(5), 5, "<code>largestPrimeFactor(5)</code> should return 5.");'
|
2018-10-04 13:37:37 +00:00
|
|
|
- text: <code>largestPrimeFactor(7)</code> should return 7.
|
2018-10-08 00:01:53 +00:00
|
|
|
testString: 'assert.strictEqual(largestPrimeFactor(7), 7, "<code>largestPrimeFactor(7)</code> should return 7.");'
|
2018-10-04 13:37:37 +00:00
|
|
|
- text: <code>largestPrimeFactor(13195)</code> should return 29.
|
2018-10-08 00:01:53 +00:00
|
|
|
testString: 'assert.strictEqual(largestPrimeFactor(13195), 29, "<code>largestPrimeFactor(13195)</code> should return 29.");'
|
2018-10-04 13:37:37 +00:00
|
|
|
- text: <code>largestPrimeFactor(600851475143)</code> should return 6857.
|
2018-10-08 00:01:53 +00:00
|
|
|
testString: 'assert.strictEqual(largestPrimeFactor(600851475143), 6857, "<code>largestPrimeFactor(600851475143)</code> should return 6857.");'
|
2018-10-04 13:37:37 +00:00
|
|
|
|
|
|
|
```
|
|
|
|
|
|
|
|
</section>
|
|
|
|
|
|
|
|
## Challenge Seed
|
|
|
|
<section id='challengeSeed'>
|
|
|
|
|
|
|
|
<div id='js-seed'>
|
|
|
|
|
|
|
|
```js
|
|
|
|
function largestPrimeFactor(number) {
|
|
|
|
// Good luck!
|
|
|
|
return true;
|
|
|
|
}
|
|
|
|
|
|
|
|
largestPrimeFactor(13195);
|
|
|
|
```
|
|
|
|
|
|
|
|
</div>
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
</section>
|
|
|
|
|
|
|
|
## Solution
|
|
|
|
<section id='solution'>
|
|
|
|
|
|
|
|
|
|
|
|
```js
|
|
|
|
const largestPrimeFactor = (number)=>{
|
|
|
|
let largestFactor = number;
|
|
|
|
for(let i = 2;i<largestFactor;i++){
|
|
|
|
if(!(largestFactor%i)){
|
|
|
|
largestFactor = largestFactor/i;
|
|
|
|
largestPrimeFactor(largestFactor);
|
|
|
|
}
|
|
|
|
}
|
|
|
|
return largestFactor;
|
|
|
|
}
|
|
|
|
```
|
|
|
|
|
|
|
|
</section>
|