29 lines
584 B
Markdown
29 lines
584 B
Markdown
---
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title: factorial
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tags: math,algorithm,recursion,beginner
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firstSeen: 2017-12-07T14:41:33+02:00
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lastUpdated: 2020-12-28T13:49:24+02:00
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---
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Calculates the factorial of a number.
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- Use recursion.
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- If `n` is less than or equal to `1`, return `1`.
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- Otherwise, return the product of `n` and the factorial of `n - 1`.
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- Throw a `TypeError` if `n` is a negative number.
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```js
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const factorial = n =>
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n < 0
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? (() => {
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throw new TypeError('Negative numbers are not allowed!');
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})()
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: n <= 1
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? 1
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: n * factorial(n - 1);
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```
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```js
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factorial(6); // 720
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```
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