122 lines
6.0 KiB
Markdown
122 lines
6.0 KiB
Markdown
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---
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title: Sum All Odd Fibonacci Numbers
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---
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 Remember to use <a>**`Read-Search-Ask`**</a> if you get stuck. Try to pair program  and write your own code 
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###  Problem Explanation:
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You will need to gather all the **Fibonacci** numbers and then check for the odd ones. Once you get the odd ones then you will add them all. The last number should be the number given as a parameter if it actually happens to be an off Fibonacci number.
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#### Relevant Links
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* <a href='https://en.wikipedia.org/wiki/Fibonacci_number' target='_blank' rel='nofollow'>Fibonacci number</a>
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##  Hint: 1
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To get the next number of the series, you need to add the current one to the previous and that will give you the next one.
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> _try to solve the problem now_
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##  Hint: 2
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To check if a number is even all you have to check is if `number % 2 == 0`.
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> _try to solve the problem now_
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##  Hint: 3
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As you get the next odd one, don't forget to add it to a global variable that can be returned at the end. `result += currNumber;` will do the trick.
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> _try to solve the problem now_
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## Spoiler Alert!
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**Solution ahead!**
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##  Basic Code Solution:
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function sumFibs(num) {
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var prevNumber = 0;
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var currNumber = 1;
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var result = 0;
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while (currNumber <= num) {
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if (currNumber % 2 !== 0) {
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result += currNumber;
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}
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currNumber += prevNumber;
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prevNumber = currNumber - prevNumber;
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}
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return result;
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}
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// test here
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sumFibs(4);
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 <a href='https://repl.it/CLnV/0' target='_blank' rel='nofollow'>Run Code</a>
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### Code Explanation:
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* Create a variable to keep record of the current and previous numbers along with the result that will be returned.
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* Use a while loop to make sure we do not go over the number given as parameter.
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* We use the modulo operand to check if the current number is odd or even. If it is even, add it to the result.
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* Complete the Fibonacci circle by rotating getting the next number and swapping values after.
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* Return the result.
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#### Relevant Links
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* <a>JS while Loop</a>
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##  Intermediate Code Solution:
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function sumFibs(num) {
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// Perform checks for the validity of the input
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if (num < 0) return -1;
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if (num === 0 || num === 1) return 1;
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// Create an array of fib numbers till num
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const arrFib = [1, 1];
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let nextFib = 0;
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// We put the new Fibonacci numbers to the front so we
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// don't need to calculate the length of the array on each
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// iteration
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while((nextFib = arrFib[0] + arrFib[1]) <= num) {
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arrFib.unshift(nextFib);
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}
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// Sum only the odd numbers and return the value
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return arrFib.reduce((acc, curr) => {
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return acc + curr * (curr % 2);
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});
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}
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// test here
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sumFibs(4);
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 <a href='https://repl.it/@kr3at0/SumAllOddFibonacciNumbers' target='_blank' rel='nofollow'>Run Code</a>
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### Code Explanation:
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* Create an array of fibonacci numbers till **num**.
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* Use `reduce()` method to find the sum of odd members of array.
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* Return the sum.
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#### Relevant Links
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* <a href='http://forum.freecodecamp.com/t/javascript-array-prototype-push/14298' target='_blank' rel='nofollow'>JS Array Prototype Push</a>
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* <a href='http://forum.freecodecamp.com/t/javascript-for-loop/14666s-Explained' target='_blank' rel='nofollow'>JS For Loops Explained</a>
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* <a href='http://forum.freecodecamp.com/t/javascript-array-prototype-reduce/14299' target='_blank' rel='nofollow'>JS Array Prototype Reduce</a>
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##  NOTES FOR CONTRIBUTIONS:
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*  **DO NOT** add solutions that are similar to any existing solutions. If you think it is **_similar but better_**, then try to merge (or replace) the existing similar solution.
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* Add an explanation of your solution.
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* Categorize the solution in one of the following categories — **Basic**, **Intermediate** and **Advanced**. 
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* Please add your username only if you have added any **relevant main contents**. ( **_DO NOT_** _remove any existing usernames_)
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> See  <a href='http://forum.freecodecamp.com/t/algorithm-article-template/14272' target='_blank' rel='nofollow'>**`Wiki Challenge Solution Template`**</a> for reference.
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