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Update a solution for "Find the Symmetric Difference" algorithm (#36379)

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* Update advanced solution

* Replace HTML links with markdown syntax

* Remove obsolete sort()

* Use spread operator instead of Array.from
This commit is contained in:
Nikolai Kiselev
2019-07-19 07:07:09 +07:00
committed by Randell Dawson
parent 392d546988
commit 7dd2fe19f3
1 changed files with 22 additions and 26 deletions
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48
guide/english/certifications/coding-interview-prep/algorithms/find-the-symmetric-difference/index.md
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@ -14,10 +14,9 @@ Following above definition, symmetric difference of three sets *A*, *B*, and *C*
#### Relevant Links ####
* <a href="https://en.wikipedia.org/wiki/Symmetric_difference" target="_blank" rel="nofollow">Symmetric difference - Wikipedia</a>
* <a href="https://www.youtube.com/watch?v=PxffSUQRkG4" target="_blank" rel="nofollow">Symmetric difference - YouTube</a>
* <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/reduce" target="_blank"
rel="nofollow">JavaScript Array.prototype.reduce()</a>
* [Symmetric difference - Wikipedia](https://en.wikipedia.org/wiki/Symmetric_difference)
* [Symmetric difference - YouTube](https://www.youtube.com/watch?v=PxffSUQRkG4)
* [Array.reduce()](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/reduce)
## ![:speech_balloon:](https://forum.freecodecamp.com/images/emoji/emoji_one/speech_balloon.png?v=3 ":speech_balloon:") Hint: 1 ##
@ -96,11 +95,11 @@ In the event of *odd number of sets* the symmetric difference will include ident
#### Relevant Links ####
* <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/statements/for" target="_blank" rel="nofollow">JavaScript for</a>
* <a href="https://developer.mozilla.org/en/docs/Web/JavaScript/Reference/Global_Objects/Array/length" target="_blank" rel="nofollow">JavaScript Array.length</a>
* <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/push" target="_blank" rel="nofollow">JavaScript Array.prototype.push()</a>
* <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/forEach" target="_blank" rel="nofollow">JavaScript Array.prototype.forEach()</a>
* <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/indexOf" target="_blank" rel="nofollow">JavaScript Array.prototype.indexOf()</a>
* [Statement for](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/statements/for)
* [Array.length](https://developer.mozilla.org/en/docs/Web/JavaScript/Reference/Global_Objects/Array/length)
* [Array.push()](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/push)
* [Array.forEach()](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/forEach)
* [Array.indexOf()](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/indexOf)
## ![:sunflower:](https://forum.freecodecamp.com/images/emoji/emoji_one/sunflower.png?v=3 ":sunflower:") Intermediate Code Solution: ##
@ -151,23 +150,21 @@ In the event of *odd number of sets* the symmetric difference will include ident
#### Relevant Links ####
* <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/slice" target="_blank" rel="nofollow">JavaScript Array.prototype.slice()</a>
* <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/filter" target="_blank" rel="nofollow">JavaScript Array.prototype.filter()</a>
* <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/concat" target="_blank" rel="nofollow">JavaScript Array.prototype.concat()</a>
* [Array.slice()](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/slice)
* [Array.filter()](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/filter)
* [Array.concat()](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/concat)
## ![:rotating_light:](https://forum.freecodecamp.com/images/emoji/emoji_one/rotating_light.png?v=3 ":rotating_light:") Advanced Code Solution: ##
```javascript
function sym() {
let argv = Array.from(arguments).reduce(diffArray);
return argv.filter((element, index, array) => index === array.indexOf(element));//remove duplicates
}
const diff = (arr1, arr2) => (
[
...arr1.filter(e => !arr2.includes(e)),
...arr2.filter(e => !arr1.includes(e)),
]
);
function diffArray(arr1, arr2) {
return arr1
.filter(element => !arr2.includes(element))
.concat(arr2.filter(element => !arr1.includes(element)));
}
const sym = (...args) => [...new Set(args.reduce(diff))];
// test here
sym([1, 2, 3], [5, 2, 1, 4]);
@ -176,14 +173,13 @@ In the event of *odd number of sets* the symmetric difference will include ident
### Code Explanation: ###
* The main function *sym()* creates an array from *arguments* and reduces its elements utilising helper function *diffArray()* to a single array.
* The main function *sym()* reduces given arrays utilising helper function *diff()* to a single array. Also, it temporary converts the result to *Set* to remove duplicates.
* The function *diffArray()* returns the symmetric difference of two arrays by picking out unique elements in parameterised arrays; *arr1* and *arr2*.
* The function *diff()* returns the symmetric difference of two arrays by picking out elements in parameterised arrays; *arr1* and *arr2*.
#### Relevant Links ####
* <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/from" target="_blank" rel="nofollow">JavaScript Array.from()</a>
* <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/filter" target="_blank" rel="nofollow">JavaScript Array.prototype.filter()</a>
* [Set](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Set)
* [Array.filter()](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/filter)
## ![:clipboard:](https://forum.freecodecamp.com/images/emoji/emoji_one/clipboard.png?v=3 ":clipboard:") NOTES FOR CONTRIBUTIONS: ##