2.4 KiB
2.4 KiB
| id | challengeType | title | forumTopicId |
|---|---|---|---|
| 5900f36e1000cf542c50fe81 | 5 | Problem 2: Even Fibonacci Numbers | 301838 |
Description
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:
1, 2, 3, 5, 8, 13, 21, 34, 55, 89, ...
By considering the terms in the Fibonacci sequence whose values do not exceed n, find the sum of the even-valued terms.
Instructions
Tests
tests:
- text: <code>fiboEvenSum(10)</code> should return a number.
testString: assert(typeof fiboEvenSum(10) === 'number');
- text: Your function should return an <code>even</code> value.
testString: assert.equal(fiboEvenSum(10) % 2 === 0, true);
- text: 'Your function should sum the even-valued Fibonacci numbers: <code>fiboEvenSum(8)</code> should return 10.'
testString: assert.strictEqual(fiboEvenSum(8), 10);
- text: <code>fiboEvenSum(10)</code> should return 10.
testString: assert.strictEqual(fiboEvenSum(10), 10);
- text: <code>fiboEvenSum(34)</code> should return 44.
testString: assert.strictEqual(fiboEvenSum(34), 44);
- text: <code>fiboEvenSum(60)</code> should return 44.
testString: assert.strictEqual(fiboEvenSum(60), 44);
- text: <code>fiboEvenSum(1000)</code> should return 798.
testString: assert.strictEqual(fiboEvenSum(1000), 798);
- text: <code>fiboEvenSum(100000)</code> should return 60696.
testString: assert.strictEqual(fiboEvenSum(100000), 60696);
- text: <code>fiboEvenSum(4000000)</code> should return 4613732.
testString: assert.strictEqual(fiboEvenSum(4000000), 4613732);
Challenge Seed
function fiboEvenSum(n) {
return true;
}
Solution
const fiboEvenSum = (number) => {
if (number <= 1) {
return 0;
} else {
let evenSum = 0,
prevFibNum = 1,
fibNum = 2; // According to problem description our Fibonacci series starts with 1, 2
for (let i = 2; fibNum <= number; i++) {
if (fibNum % 2 == 0) {
evenSum += fibNum;
}
[prevFibNum, fibNum] = [fibNum, prevFibNum + fibNum];
}
return evenSum;
}
};