79d9012432
* fix(curriculum): tests quotes * fix(curriculum): fill seed-teardown * fix(curriculum): fix tests and remove unneeded seed-teardown
106 lines
3.1 KiB
Markdown
106 lines
3.1 KiB
Markdown
---
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id: 5900f3781000cf542c50fe8b
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challengeType: 5
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title: 'Problem 12: Highly divisible triangular number'
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---
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## Description
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<section id='description'>
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The sequence of triangle numbers is generated by adding the natural numbers. So the 7th triangle number would be 1 + 2 + 3 + 4 + 5 + 6 + 7 = 28. The first ten terms would be:
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<div style='text-align: center;'>1, 3, 6, 10, 15, 21, 28, 36, 45, 55, ...</div>
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Let us list the factors of the first seven triangle numbers:
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<div style='padding-left: 4em;'><b>1:</b> 1</div>
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<div style='padding-left: 4em;'><b>3:</b> 1, 3</div>
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<div style='padding-left: 4em;'><b>6:</b> 1, 2, 3, 6</div>
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<div style='padding-left: 4em;'><b>10:</b> 1, 2, 5, 10</div>
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<div style='padding-left: 4em;'><b>15:</b> 1, 3, 5, 15</div>
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<div style='padding-left: 4em;'><b>21:</b> 1, 3, 7, 21</div>
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<div style='padding-left: 4em;'><b>28:</b> 1, 2, 4, 7, 14, 28</div>
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We can see that 28 is the first triangle number to have over five divisors.
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What is the value of the first triangle number to have over <code>n</code> divisors?
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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>divisibleTriangleNumber(5)</code> should return 28.
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testString: assert.strictEqual(divisibleTriangleNumber(5), 28, '<code>divisibleTriangleNumber(5)</code> should return 28.');
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- text: <code>divisibleTriangleNumber(23)</code> should return 630.
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testString: assert.strictEqual(divisibleTriangleNumber(23), 630, '<code>divisibleTriangleNumber(23)</code> should return 630.');
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- text: <code>divisibleTriangleNumber(167)</code> should return 1385280.
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testString: assert.strictEqual(divisibleTriangleNumber(167), 1385280, '<code>divisibleTriangleNumber(167)</code> should return 1385280.');
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- text: <code>divisibleTriangleNumber(374)</code> should return 17907120.
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testString: assert.strictEqual(divisibleTriangleNumber(374), 17907120, '<code>divisibleTriangleNumber(374)</code> should return 17907120.');
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- text: <code>divisibleTriangleNumber(500)</code> should return 76576500.
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testString: assert.strictEqual(divisibleTriangleNumber(500), 76576500, '<code>divisibleTriangleNumber(500)</code> should return 76576500.');
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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 divisibleTriangleNumber(n) {
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// Good luck!
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return true;
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}
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divisibleTriangleNumber(500);
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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 divisibleTriangleNumber(n) {
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let counter = 1;
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let triangleNumber = counter++;
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function getFactors(num) {
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let factors = [];
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let possibleFactor = 1;
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let sqrt = Math.sqrt(num);
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while (possibleFactor <= sqrt) {
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if (num % possibleFactor == 0) {
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factors.push(possibleFactor);
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var otherPossibleFactor = num / possibleFactor;
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if (otherPossibleFactor > possibleFactor) {
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factors.push(otherPossibleFactor);
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}
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}
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possibleFactor++;
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}
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return factors;
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}
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while (getFactors(triangleNumber).length < n) {
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triangleNumber += counter++;
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}
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console.log(triangleNumber)
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return triangleNumber;
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}
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```
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</section>
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