74 lines
1.4 KiB
Markdown
74 lines
1.4 KiB
Markdown
|
---
|
||
|
title: Evaluate binomial coefficients
|
||
|
id: 598de241872ef8353c58a7a2
|
||
|
challengeType: 5
|
||
|
forumTopicId: 302259
|
||
|
---
|
||
|
|
||
|
## Description
|
||
|
<section id='description'>
|
||
|
Write a function to calculate the binomial coefficient for the given value of n and k.
|
||
|
This formula is recommended:
|
||
|
$\binom{n}{k} = \frac{n!}{(n-k)!k!} = \frac{n(n-1)(n-2)\ldots(n-k+1)}{k(k-1)(k-2)\ldots 1}$
|
||
|
</section>
|
||
|
|
||
|
## Instructions
|
||
|
<section id='instructions'>
|
||
|
|
||
|
</section>
|
||
|
|
||
|
## Tests
|
||
|
<section id='tests'>
|
||
|
|
||
|
```yml
|
||
|
tests:
|
||
|
- text: <code>binom</code> should be a function.
|
||
|
testString: assert(typeof binom === 'function');
|
||
|
- text: <code>binom(5,3)</code> should return 10.
|
||
|
testString: assert.equal(binom(5, 3), 10);
|
||
|
- text: <code>binom(7,2)</code> should return 21.
|
||
|
testString: assert.equal(binom(7, 2), 21);
|
||
|
- text: <code>binom(10,4)</code> should return 210.
|
||
|
testString: assert.equal(binom(10, 4), 210);
|
||
|
- text: <code>binom(6,1)</code> should return 6.
|
||
|
testString: assert.equal(binom(6, 1), 6);
|
||
|
- text: <code>binom(12,8)</code> should return 495.
|
||
|
testString: assert.equal(binom(12, 8), 495);
|
||
|
|
||
|
```
|
||
|
|
||
|
</section>
|
||
|
|
||
|
## Challenge Seed
|
||
|
<section id='challengeSeed'>
|
||
|
|
||
|
<div id='js-seed'>
|
||
|
|
||
|
```js
|
||
|
function binom(n, k) {
|
||
|
|
||
|
}
|
||
|
```
|
||
|
|
||
|
</div>
|
||
|
|
||
|
|
||
|
|
||
|
</section>
|
||
|
|
||
|
## Solution
|
||
|
<section id='solution'>
|
||
|
|
||
|
|
||
|
```js
|
||
|
function binom(n, k) {
|
||
|
let coeff = 1;
|
||
|
for (let i = n - k + 1; i <= n; i++) coeff *= i;
|
||
|
for (let i = 1; i <= k; i++) coeff /= i;
|
||
|
return coeff;
|
||
|
}
|
||
|
|
||
|
```
|
||
|
|
||
|
</section>
|