69 lines
1.6 KiB
Markdown
69 lines
1.6 KiB
Markdown
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---
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title: Factorial
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id: 597b2b2a2702b44414742771
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challengeType: 5
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videoUrl: ''
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localeTitle: 阶乘
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---
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## Description
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<section id="description"><p>编写一个函数来返回一个数字的阶乘。 </p><p>一个数字的因子由下式给出： </p> N！ = n *（n-1）*（n-2）* ..... * 1 <p>例如：3！ = 3 * 2 * 1 = 6 4！ = 4 * 3 * 2 * 1 = 24 </p><p>注意：0！ = 1 </p></section>
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## Instructions
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<section id="instructions">
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</section>
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## Tests
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<section id='tests'>
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```yml
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tests:
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- text: <code>factorial</code>是一种功能。
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testString: 'assert(typeof factorial === "function", "<code>factorial</code> is a function.");'
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- text: <code>factorial(2)</code>应该返回一个数字。
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testString: 'assert(typeof factorial(2) === "number", "<code>factorial(2)</code> should return a number.");'
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- text: <code>factorial(3)</code>应该返回6.“）
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testString: 'assert.equal(factorial(3),results[0],"<code>factorial(3)</code> should return 6.");'
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- text: <code>factorial(3)</code>应返回120.“）
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testString: 'assert.equal(factorial(5),results[1],"<code>factorial(3)</code> should return 120.");'
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- text: '<code>factorial(3)</code>应返回3,628,800。“）'
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testString: 'assert.equal(factorial(10),results[2],"<code>factorial(3)</code> should return 3,628,800.");'
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```
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</section>
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## Challenge Seed
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<section id='challengeSeed'>
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<div id='js-seed'>
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```js
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function factorial (n) {
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// Good luck!
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}
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```
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</div>
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### After Test
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<div id='js-teardown'>
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```js
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console.info('after the test');
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```
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</div>
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</section>
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## Solution
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<section id='solution'>
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```js
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// solution required
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```
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</section>
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