122 lines
2.7 KiB
Markdown
122 lines
2.7 KiB
Markdown
---
|
|
id: 5a23c84252665b21eecc8046
|
|
title: Symmetric difference
|
|
challengeType: 5
|
|
forumTopicId: 16086
|
|
dashedName: symmetric-difference
|
|
---
|
|
|
|
# --description--
|
|
|
|
Given two [set](https://rosettacode.org/wiki/set)s *A* and *B*, compute $(A \\setminus B) \\cup (B \\setminus A).$ That is, enumerate the items that are in *A* or *B* but not both. This set is called the [symmetric difference](https://en.wikipedia.org/wiki/Symmetric difference) of *A* and *B*. In other words: $(A \\cup B) \\setminus (A \\cap B)$ (the set of items that are in at least one of *A* or *B* minus the set of items that are in both *A* and *B*).
|
|
|
|
# --instructions--
|
|
|
|
Write a function that takes two arrays as parameters and returns the symmetric difference. Sort the resultant array before returning it.
|
|
|
|
# --hints--
|
|
|
|
`symmetricDifference` should be a function.
|
|
|
|
```js
|
|
assert(typeof symmetricDifference == 'function');
|
|
```
|
|
|
|
`symmetricDifference(["John", "Bob", "Mary", "Serena"], ["Jim", "Mary", "John", "Bob"])` should return an array.
|
|
|
|
```js
|
|
assert(
|
|
Array.isArray(
|
|
symmetricDifference(
|
|
['John', 'Bob', 'Mary', 'Serena'],
|
|
['Jim', 'Mary', 'John', 'Bob']
|
|
)
|
|
)
|
|
);
|
|
```
|
|
|
|
`symmetricDifference(["John", "Bob", "Mary", "Serena"], ["Jim", "Mary", "John", "Bob"])` should return `["Jim", "Serena"]`.
|
|
|
|
```js
|
|
assert.deepEqual(
|
|
symmetricDifference(
|
|
['John', 'Bob', 'Mary', 'Serena'],
|
|
['Jim', 'Mary', 'John', 'Bob']
|
|
),
|
|
['Jim', 'Serena']
|
|
);
|
|
```
|
|
|
|
`symmetricDifference([1, 2, 3], [3, 4])` should return `[1, 2, 4]`.
|
|
|
|
```js
|
|
assert.deepEqual(symmetricDifference([1, 2, 3], [3, 4]), [1, 2, 4]);
|
|
```
|
|
|
|
`symmetricDifference([1, 2, 3, 4, 5], [3, 4, 8, 7])` should return `[1, 2, 5, 7, 8]`.
|
|
|
|
```js
|
|
assert.deepEqual(symmetricDifference([1, 2, 3, 4, 5], [3, 4, 8, 7]), [
|
|
1,
|
|
2,
|
|
5,
|
|
7,
|
|
8
|
|
]);
|
|
```
|
|
|
|
`symmetricDifference([1, 2, 3, 4, 5, 6, 7, 8], [1, 3, 5, 6, 7, 8, 9])` should return `[2, 4, 9]`.
|
|
|
|
```js
|
|
assert.deepEqual(
|
|
symmetricDifference([1, 2, 3, 4, 5, 6, 7, 8], [1, 3, 5, 6, 7, 8, 9]),
|
|
[2, 4, 9]
|
|
);
|
|
```
|
|
|
|
`symmetricDifference([1, 2, 4, 7, 9], [2, 3, 7, 8, 9])` should return `[1, 3, 4, 8]`.
|
|
|
|
```js
|
|
assert.deepEqual(symmetricDifference([1, 2, 4, 7, 9], [2, 3, 7, 8, 9]), [
|
|
1,
|
|
3,
|
|
4,
|
|
8
|
|
]);
|
|
```
|
|
|
|
# --seed--
|
|
|
|
## --seed-contents--
|
|
|
|
```js
|
|
function symmetricDifference(A, B) {
|
|
|
|
}
|
|
```
|
|
|
|
# --solutions--
|
|
|
|
```js
|
|
function symmetricDifference(A, B) {
|
|
function relative_complement(A, B) {
|
|
return A.filter(function(elem) {
|
|
return B.indexOf(elem) == -1;
|
|
});
|
|
}
|
|
|
|
function unique(ary) {
|
|
var u = ary.concat().sort();
|
|
for (var i = 1; i < u.length; ) {
|
|
if (u[i - 1] === u[i]) u.splice(i, 1);
|
|
else i++;
|
|
}
|
|
return u;
|
|
}
|
|
|
|
return unique(
|
|
relative_complement(A, B).concat(relative_complement(B, A))
|
|
).sort();
|
|
}
|
|
```
|