151 lines
3.8 KiB
Markdown
151 lines
3.8 KiB
Markdown
---
|
|
id: a3f503de51cf954ede28891d
|
|
title: Find the Symmetric Difference
|
|
challengeType: 5
|
|
forumTopicId: 301611
|
|
dashedName: find-the-symmetric-difference
|
|
---
|
|
|
|
# --description--
|
|
|
|
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}`.
|
|
|
|
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}`.
|
|
|
|
# --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 (*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]);
|
|
```
|
|
|
|
`sym([1, 2, 3], [5, 2, 1, 4])` should contain only three elements.
|
|
|
|
```js
|
|
assert.equal(sym([1, 2, 3], [5, 2, 1, 4]).length, 3);
|
|
```
|
|
|
|
`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) {
|
|
return args;
|
|
}
|
|
|
|
sym([1, 2, 3], [5, 2, 1, 4]);
|
|
```
|
|
|
|
# --solutions--
|
|
|
|
```js
|
|
function sym() {
|
|
var arrays = [].slice.call(arguments);
|
|
return arrays.reduce(function (symDiff, arr) {
|
|
return symDiff.concat(arr).filter(function (val, idx, theArr) {
|
|
return theArr.indexOf(val) === idx
|
|
&& (symDiff.indexOf(val) === -1 || arr.indexOf(val) === -1);
|
|
});
|
|
});
|
|
}
|
|
sym([1, 2, 3], [5, 2, 1, 4]);
|
|
```
|