35 lines
735 B
Markdown
35 lines
735 B
Markdown
---
|
|
title: Prime factors of number
|
|
tags: math,algorithm
|
|
expertise: beginner
|
|
author: maciv
|
|
cover: blog_images/dark-leaves-3.jpg
|
|
firstSeen: 2020-12-28T13:11:01+02:00
|
|
lastUpdated: 2020-12-28T13:11:01+02:00
|
|
---
|
|
|
|
Finds the prime factors of a given number using the trial division algorithm.
|
|
|
|
- Use a `while` loop to iterate over all possible prime factors, starting with `2`.
|
|
- If the current factor, `f`, exactly divides `n`, add `f` to the factors array and divide `n` by `f`. Otherwise, increment `f` by one.
|
|
|
|
```js
|
|
const primeFactors = n => {
|
|
let a = [],
|
|
f = 2;
|
|
while (n > 1) {
|
|
if (n % f === 0) {
|
|
a.push(f);
|
|
n /= f;
|
|
} else {
|
|
f++;
|
|
}
|
|
}
|
|
return a;
|
|
};
|
|
```
|
|
|
|
```js
|
|
primeFactors(147); // [3, 7, 7]
|
|
```
|