81 lines
1.0 KiB
Markdown
81 lines
1.0 KiB
Markdown
---
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id: 597b2b2a2702b44414742771
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title: Factorial
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challengeType: 5
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forumTopicId: 302263
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dashedName: factorial
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---
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# --description--
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Write a function to return the factorial of a number.
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Factorial of a number is given by:
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<pre><big>n! = n * (n-1) * (n-2) * ..... * 1</big>
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</pre>
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For example:
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<ul>
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<li><code>3! = 3 * 2 * 1 = 6</code></li>
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<li><code>4! = 4 * 3 * 2 * 1 = 24</code></li>
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</ul>
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**Note:** `0! = 1`
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# --hints--
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`factorial` should be a function.
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```js
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assert(typeof factorial === 'function');
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```
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`factorial(2)` should return a number.
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```js
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assert(typeof factorial(2) === 'number');
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```
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`factorial(3)` should return 6.
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```js
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assert.equal(factorial(3), 6);
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```
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`factorial(5)` should return 120.
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```js
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assert.equal(factorial(5), 120);
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```
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`factorial(10)` should return 3,628,800.
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```js
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assert.equal(factorial(10), 3628800);
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```
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# --seed--
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## --seed-contents--
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```js
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function factorial(n) {
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}
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```
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# --solutions--
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```js
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function factorial(n) {
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let sum = 1;
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while (n > 1) {
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sum *= n;
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n--;
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}
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return sum;
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}
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```
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