84 lines
1.8 KiB
Markdown
84 lines
1.8 KiB
Markdown
---
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title: Factors of an integer
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id: 597f1e7fbc206f0e9ba95dc4
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challengeType: 5
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---
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## Description
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<section id='description'>
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<p>Write a function that returns the factors of a positive integer.</p><p>These factors are the positive integers by which the number being factored can be divided to yield a positive integer result.</p>
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///
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</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>factors</code> is a function.
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testString: assert(typeof factors === 'function', '<code>factors</code> is a function.');
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- text: <code>factors(45)</code> should return <code>[1,3,5,9,15,45]</code>.
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testString: assert.deepEqual(factors(45), ans[0], '<code>factors(45)</code> should return <code>[1,3,5,9,15,45]</code>.');
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- text: <code>factors(53)</code> should return <code>[1,53]</code>.
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testString: assert.deepEqual(factors(53), ans[1], '<code>factors(53)</code> should return <code>[1,53]</code>.');
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- text: <code>factors(64)</code> should return <code>[1,2,4,8,16,32,64]</code>.
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testString: assert.deepEqual(factors(64), ans[2], '<code>factors(64)</code> should return <code>[1,2,4,8,16,32,64]</code>.');
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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 factors (num) {
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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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const ans=[[1,3,5,9,15,45],[1,53],[1,2,4,8,16,32,64]];
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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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function factors(num)
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{
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let n_factors = [], i, sqr=Math.floor(Math.sqrt(num));
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for (i = 1; i <=sqr ; i += 1)
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if (num % i === 0)
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{
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n_factors.push(i);
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if (num / i !== i)
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n_factors.push(num / i);
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}
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n_factors.sort(function(a, b){return a - b;});
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return n_factors;
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}
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```
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</section>
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