84 lines
1.9 KiB
Markdown
84 lines
1.9 KiB
Markdown
---
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id: 5900f36e1000cf542c50fe81
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challengeType: 5
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title: 'Problem 2: Even Fibonacci Numbers'
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forumTopicId: 301838
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---
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## Description
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<section id='description'>
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Each new term in the Fibonacci sequence is generated by adding the previous two terms. By starting with 1 and 2, the first 10 terms will be:
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<div style='text-align: center;'>1, 2, 3, 5, 8, 13, 21, 34, 55, 89, ...</div>
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By considering the terms in the Fibonacci sequence that do not exceed the <code>n</code>th term, find the sum of the even-valued terms.
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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>fiboEvenSum(10)</code> should return 44.
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testString: assert.strictEqual(fiboEvenSum(10), 44);
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- text: <code>fiboEvenSum(18)</code> should return 3382.
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testString: assert.strictEqual(fiboEvenSum(18), 3382);
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- text: <code>fiboEvenSum(23)</code> should return 60696.
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testString: assert.strictEqual(fiboEvenSum(23), 60696);
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- text: <code>fiboEvenSum(43)</code> should return 350704366.
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testString: assert.strictEqual(fiboEvenSum(43), 350704366);
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- text: Your function should return an <code>even</code> value.
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testString: assert.equal(fiboEvenSum(10) % 2 === 0, true);
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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 fiboEvenSum(n) {
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// You can do it!
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return true;
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}
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fiboEvenSum(10);
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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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const fiboEvenSum = (number) => {
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if (number <= 1) {
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return 0;
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} else {
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let evenSum = 2, first = 1, second = 2, fibNum; // According to problem description our Fibonacci series starts with 1, 2
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for (let i = 3; i <= number; i++) {
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fibNum = first + second;
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first = second;
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second = fibNum;
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if (fibNum % 2 == 0) {
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evenSum += fibNum;
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}
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}
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return evenSum;
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}
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}
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```
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</section>
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