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feat: Add guide article and update its challenge (#36371)

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* feat: Add guide article and update its challenge

* Update guide/english/certifications/javascript-algorithms-and-data-structures/basic-javascript/replace-loops-using-recursion/index.md

Co-Authored-By: Randell Dawson <5313213+RandellDawson@users.noreply.github.com>

* Update guide/english/certifications/javascript-algorithms-and-data-structures/basic-javascript/replace-loops-using-recursion/index.md

Co-Authored-By: Randell Dawson <5313213+RandellDawson@users.noreply.github.com>

* Update guide/english/certifications/javascript-algorithms-and-data-structures/basic-javascript/replace-loops-using-recursion/index.md

Co-Authored-By: Randell Dawson <5313213+RandellDawson@users.noreply.github.com>

* Update guide/english/certifications/javascript-algorithms-and-data-structures/basic-javascript/replace-loops-using-recursion/index.md

Co-Authored-By: Randell Dawson <5313213+RandellDawson@users.noreply.github.com>

* fix: Stop hints from being hidden

* fix: Improve the wording.

* Update index.md

Fixed per suggestion

* Update index.md

Fixed per suggestion
This commit is contained in:
Oliver Eyton-Williams
2019-07-19 23:14:28 +02:00
committed by Quincy Larson
parent 35c284e9a7
commit 6078081a3f
2 changed files with 41 additions and 3 deletions
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guide/english/certifications/javascript-algorithms-and-data-structures/basic-javascript/replace-loops-using-recursion/index.md Normal file
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---
title: Replace Loops using Recursion
---
# Replace Loops using Recursion
### Hint 1:
When `n <= 0` `sum(arr, n)` returns `arr[0]`.
### Hint 2:
When `n` is larger than 0 `sum(arr, n)` returns `sum(arr, n - 1) + arr[n]`
## Basic code solution:
<details><summary>(Click to reveal)</summary>
```js
function sum(arr, n) {
if (n <= 0) {
return arr[0];
} else {
return sum(arr, n - 1) + arr[n];
}
}
```
</details>
### Code explanation
The `if` statement checks to see if `sum` is evaluating the base case, `n <= 0`, or not. If it is, then `sum` returns the answer, `arr[0]` - the sum of elements from 0 to 0 inclusive. Otherwise it recurses by evaluating a simpler function call, `sum(arr, n - 1)`. Once that returns it adds a single array element, `arr[n]`, to it and returns that sum.
### Resources
- [Recursive Functions - *MDN JavaScript reference*](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Guide/Functions#Recursion)