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and change all the challenges to new `md` format.
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Oliver Eyton-Williams
2020-11-27 19:02:05 +01:00
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curriculum/challenges/english/10-coding-interview-prep/algorithms/find-the-symmetric-difference.md
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@ -5,60 +5,125 @@ challengeType: 5
forumTopicId: 301611
---
## Description
<section id='description'>
The mathematical term <dfn>symmetric difference</dfn> (<code>&xutri;</code> or <code>&oplus;</code>) of two sets is the set of elements which are in either of the two sets but not in both. For example, for sets <code>A = {1, 2, 3}</code> and <code>B = {2, 3, 4}</code>, <code>A &xutri; B = {1, 4}</code>.
# --description--
Symmetric difference is a binary operation, which means it operates on only two elements. So to evaluate an expression involving symmetric differences among <em>three</em> elements (<code>A &xutri; B &xutri; C</code>), you must complete one operation at a time. Thus, for sets <code>A</code> and <code>B</code> above, and <code>C = {2, 3}</code>, <code>A &xutri; B &xutri; C = (A &xutri; B) &xutri; C = {1, 4} &xutri; {2, 3} = {1, 2, 3, 4}</code>.
</section>
The mathematical term <dfn>symmetric difference</dfn> (`△` or `⊕`) of two sets is the set of elements which are in either of the two sets but not in both. For example, for sets `A = {1, 2, 3}` and `B = {2, 3, 4}`, `A △ B = {1, 4}`.
## Instructions
<section id='instructions'>
Create a function that takes two or more arrays and returns an array of their symmetric difference. The returned array must contain only unique values (<em>no duplicates</em>).
</section>
Symmetric difference is a binary operation, which means it operates on only two elements. So to evaluate an expression involving symmetric differences among *three* elements (`A △ B △ C`), you must complete one operation at a time. Thus, for sets `A` and `B` above, and `C = {2, 3}`, `A △ B △ C = (A △ B) △ C = {1, 4} △ {2, 3} = {1, 2, 3, 4}`.
## Tests
<section id='tests'>
# --instructions--
```yml
tests:
- text: <code>sym([1, 2, 3], [5, 2, 1, 4])</code> should return <code>[3, 4, 5]</code>.
testString: assert.sameMembers(sym([1, 2, 3], [5, 2, 1, 4]), [3, 4, 5]);
- text: <code>sym([1, 2, 3], [5, 2, 1, 4])</code> should contain only three elements.
testString: assert.equal(sym([1, 2, 3], [5, 2, 1, 4]).length, 3);
- text: <code>sym([1, 2, 3, 3], [5, 2, 1, 4])</code> should return <code>[3, 4, 5]</code>.
testString: assert.sameMembers(sym([1, 2, 3, 3], [5, 2, 1, 4]), [3, 4, 5]);
- text: <code>sym([1, 2, 3, 3], [5, 2, 1, 4])</code> should contain only three elements.
testString: assert.equal(sym([1, 2, 3, 3], [5, 2, 1, 4]).length, 3);
- text: <code>sym([1, 2, 3], [5, 2, 1, 4, 5])</code> should return <code>[3, 4, 5]</code>.
testString: assert.sameMembers(sym([1, 2, 3], [5, 2, 1, 4, 5]), [3, 4, 5]);
- text: <code>sym([1, 2, 3], [5, 2, 1, 4, 5])</code> should contain only three elements.
testString: assert.equal(sym([1, 2, 3], [5, 2, 1, 4, 5]).length, 3);
- text: <code>sym([1, 2, 5], [2, 3, 5], [3, 4, 5])</code> should return <code>[1, 4, 5]</code>
testString: assert.sameMembers(sym([1, 2, 5], [2, 3, 5], [3, 4, 5]), [1, 4, 5]);
- text: <code>sym([1, 2, 5], [2, 3, 5], [3, 4, 5])</code> should contain only three elements.
testString: assert.equal(sym([1, 2, 5], [2, 3, 5], [3, 4, 5]).length, 3);
- text: <code>sym([1, 1, 2, 5], [2, 2, 3, 5], [3, 4, 5, 5])</code> should return <code>[1, 4, 5]</code>.
testString: assert.sameMembers(sym([1, 1, 2, 5], [2, 2, 3, 5], [3, 4, 5, 5]), [1, 4, 5]);
- text: <code>sym([1, 1, 2, 5], [2, 2, 3, 5], [3, 4, 5, 5])</code> should contain only three elements.
testString: assert.equal(sym([1, 1, 2, 5], [2, 2, 3, 5], [3, 4, 5, 5]).length, 3);
- text: <code>sym([3, 3, 3, 2, 5], [2, 1, 5, 7], [3, 4, 6, 6], [1, 2, 3])</code> should return <code>[2, 3, 4, 6, 7]</code>.
testString: assert.sameMembers(sym([3, 3, 3, 2, 5], [2, 1, 5, 7], [3, 4, 6, 6], [1, 2, 3]), [2, 3, 4, 6, 7]);
- text: <code>sym([3, 3, 3, 2, 5], [2, 1, 5, 7], [3, 4, 6, 6], [1, 2, 3])</code> should contain only five elements.
testString: assert.equal(sym([3, 3, 3, 2, 5], [2, 1, 5, 7], [3, 4, 6, 6], [1, 2, 3]).length, 5);
- text: <code>sym([3, 3, 3, 2, 5], [2, 1, 5, 7], [3, 4, 6, 6], [1, 2, 3], [5, 3, 9, 8], [1])</code> should return <code>[1, 2, 4, 5, 6, 7, 8, 9]</code>.
testString: assert.sameMembers(sym([3, 3, 3, 2, 5], [2, 1, 5, 7], [3, 4, 6, 6], [1, 2, 3], [5, 3, 9, 8], [1]), [1, 2, 4, 5, 6, 7, 8, 9]);
- text: <code>sym([3, 3, 3, 2, 5], [2, 1, 5, 7], [3, 4, 6, 6], [1, 2, 3], [5, 3, 9, 8], [1])</code> should contain only eight elements.
testString: assert.equal(sym([3, 3, 3, 2, 5], [2, 1, 5, 7], [3, 4, 6, 6], [1, 2, 3], [5, 3, 9, 8], [1]).length, 8);
Create a function that takes two or more arrays and returns an array of their symmetric difference. The returned array must contain only unique values (*no duplicates*).
# --hints--
`sym([1, 2, 3], [5, 2, 1, 4])` should return `[3, 4, 5]`.
```js
assert.sameMembers(sym([1, 2, 3], [5, 2, 1, 4]), [3, 4, 5]);
```
</section>
`sym([1, 2, 3], [5, 2, 1, 4])` should contain only three elements.
## Challenge Seed
<section id='challengeSeed'>
```js
assert.equal(sym([1, 2, 3], [5, 2, 1, 4]).length, 3);
```
<div id='js-seed'>
`sym([1, 2, 3, 3], [5, 2, 1, 4])` should return `[3, 4, 5]`.
```js
assert.sameMembers(sym([1, 2, 3, 3], [5, 2, 1, 4]), [3, 4, 5]);
```
`sym([1, 2, 3, 3], [5, 2, 1, 4])` should contain only three elements.
```js
assert.equal(sym([1, 2, 3, 3], [5, 2, 1, 4]).length, 3);
```
`sym([1, 2, 3], [5, 2, 1, 4, 5])` should return `[3, 4, 5]`.
```js
assert.sameMembers(sym([1, 2, 3], [5, 2, 1, 4, 5]), [3, 4, 5]);
```
`sym([1, 2, 3], [5, 2, 1, 4, 5])` should contain only three elements.
```js
assert.equal(sym([1, 2, 3], [5, 2, 1, 4, 5]).length, 3);
```
`sym([1, 2, 5], [2, 3, 5], [3, 4, 5])` should return `[1, 4, 5]`
```js
assert.sameMembers(sym([1, 2, 5], [2, 3, 5], [3, 4, 5]), [1, 4, 5]);
```
`sym([1, 2, 5], [2, 3, 5], [3, 4, 5])` should contain only three elements.
```js
assert.equal(sym([1, 2, 5], [2, 3, 5], [3, 4, 5]).length, 3);
```
`sym([1, 1, 2, 5], [2, 2, 3, 5], [3, 4, 5, 5])` should return `[1, 4, 5]`.
```js
assert.sameMembers(sym([1, 1, 2, 5], [2, 2, 3, 5], [3, 4, 5, 5]), [1, 4, 5]);
```
`sym([1, 1, 2, 5], [2, 2, 3, 5], [3, 4, 5, 5])` should contain only three elements.
```js
assert.equal(sym([1, 1, 2, 5], [2, 2, 3, 5], [3, 4, 5, 5]).length, 3);
```
`sym([3, 3, 3, 2, 5], [2, 1, 5, 7], [3, 4, 6, 6], [1, 2, 3])` should return `[2, 3, 4, 6, 7]`.
```js
assert.sameMembers(
sym([3, 3, 3, 2, 5], [2, 1, 5, 7], [3, 4, 6, 6], [1, 2, 3]),
[2, 3, 4, 6, 7]
);
```
`sym([3, 3, 3, 2, 5], [2, 1, 5, 7], [3, 4, 6, 6], [1, 2, 3])` should contain only five elements.
```js
assert.equal(
sym([3, 3, 3, 2, 5], [2, 1, 5, 7], [3, 4, 6, 6], [1, 2, 3]).length,
5
);
```
`sym([3, 3, 3, 2, 5], [2, 1, 5, 7], [3, 4, 6, 6], [1, 2, 3], [5, 3, 9, 8], [1])` should return `[1, 2, 4, 5, 6, 7, 8, 9]`.
```js
assert.sameMembers(
sym(
[3, 3, 3, 2, 5],
[2, 1, 5, 7],
[3, 4, 6, 6],
[1, 2, 3],
[5, 3, 9, 8],
[1]
),
[1, 2, 4, 5, 6, 7, 8, 9]
);
```
`sym([3, 3, 3, 2, 5], [2, 1, 5, 7], [3, 4, 6, 6], [1, 2, 3], [5, 3, 9, 8], [1])` should contain only eight elements.
```js
assert.equal(
sym([3, 3, 3, 2, 5], [2, 1, 5, 7], [3, 4, 6, 6], [1, 2, 3], [5, 3, 9, 8], [1])
.length,
8
);
```
# --seed--
## --seed-contents--
```js
function sym(args) {
@ -68,15 +133,7 @@ function sym(args) {
sym([1, 2, 3], [5, 2, 1, 4]);
```
</div>
</section>
## Solution
<section id='solution'>
# --solutions--
```js
function sym() {
@ -89,7 +146,4 @@ function sym() {
});
}
sym([1, 2, 3], [5, 2, 1, 4]);
```
</section>