65 lines
2.3 KiB
Markdown
65 lines
2.3 KiB
Markdown
|
---
|
||
|
|
title: Entropy
|
||
|
|
id: 599d15309e88c813a40baf58
|
||
|
|
challengeType: 5
|
||
|
|
videoUrl: ''
|
||
|
|
localeTitle: Entropia
|
||
|
|
---
|
||
|
|
|
||
|
|
## Description
|
||
|
|
<section id="description"> Tarefa: <p> Calcule a entropia de Shannon H de uma determinada string de entrada. </p><p> Dada a variável aleatória discreta $ X $ que é uma cadeia de $ N $ "símbolos" (caracteres totais) consistindo de $ n $ caracteres diferentes (n = 2 para binário), a entropia de Shannon de X em bits / símbolo é: </p><p> $ H_2 (X) = - \ sum_ {i = 1} ^ n \ frac {count_i} {N} \ log_2 \ left (\ frac {count_i} {N} \ right) $ </p><p> onde $ count_i $ é a contagem do caractere $ n_i $. </p></section>
|
||
|
|
|
||
|
|
## Instructions
|
||
|
|
<section id="instructions">
|
||
|
|
</section>
|
||
|
|
|
||
|
|
## Tests
|
||
|
|
<section id='tests'>
|
||
|
|
|
||
|
|
```yml
|
||
|
|
tests:
|
||
|
|
- text: <code>entropy</code> é uma função.
|
||
|
|
testString: 'assert(typeof entropy === "function", "<code>entropy</code> is a function.");'
|
||
|
|
- text: <code>entropy("0")</code> deve retornar <code>0</code>
|
||
|
|
testString: 'assert.equal(entropy("0"), 0, "<code>entropy("0")</code> should return <code>0</code>");'
|
||
|
|
- text: <code>entropy("01")</code> deve retornar <code>1</code>
|
||
|
|
testString: 'assert.equal(entropy("01"), 1, "<code>entropy("01")</code> should return <code>1</code>");'
|
||
|
|
- text: <code>entropy("0123")</code> deve retornar <code>2</code>
|
||
|
|
testString: 'assert.equal(entropy("0123"), 2, "<code>entropy("0123")</code> should return <code>2</code>");'
|
||
|
|
- text: <code>entropy("01234567")</code> deve retornar <code>3</code>
|
||
|
|
testString: 'assert.equal(entropy("01234567"), 3, "<code>entropy("01234567")</code> should return <code>3</code>");'
|
||
|
|
- text: <code>entropy("0123456789abcdef")</code> deve retornar <code>4</code>
|
||
|
|
testString: 'assert.equal(entropy("0123456789abcdef"), 4, "<code>entropy("0123456789abcdef")</code> should return <code>4</code>");'
|
||
|
|
- text: <code>entropy("1223334444")</code> deve retornar <code>1.8464393446710154</code>
|
||
|
|
testString: 'assert.equal(entropy("1223334444"), 1.8464393446710154, "<code>entropy("1223334444")</code> should return <code>1.8464393446710154</code>");'
|
||
|
|
|
||
|
|
```
|
||
|
|
|
||
|
|
</section>
|
||
|
|
|
||
|
|
## Challenge Seed
|
||
|
|
<section id='challengeSeed'>
|
||
|
|
|
||
|
|
<div id='js-seed'>
|
||
|
|
|
||
|
|
```js
|
||
|
|
function entropy (s) {
|
||
|
|
// Good luck!
|
||
|
|
}
|
||
|
|
|
||
|
|
```
|
||
|
|
|
||
|
|
</div>
|
||
|
|
|
||
|
|
|
||
|
|
|
||
|
|
</section>
|
||
|
|
|
||
|
|
## Solution
|
||
|
|
<section id='solution'>
|
||
|
|
|
||
|
|
```js
|
||
|
|
// solution required
|
||
|
|
```
|
||
|
|
</section>
|