82 lines
3.8 KiB
Markdown
82 lines
3.8 KiB
Markdown
---
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id: 5a23c84252665b21eecc8046
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title: Symmetric difference
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challengeType: 5
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---
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## Description
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<section id='description'>
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Given two <a href="http://rosettacode.org/wiki/set">set</a>s <i>A</i> and <i>B</i>, compute $(A \setminus B) \cup (B \setminus A).$
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That is, enumerate the items that are in <i>A</i> or <i>B</i> but not both. This set is called the <a href="https://en.wikipedia.org/wiki/Symmetric difference">symmetric difference</a> of <i>A</i> and <i>B</i>.
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In other words: $(A \cup B) \setminus (A \cap B)$ (the set of items that are in at least one of <i>A</i> or <i>B</i> minus the set of items that are in both <i>A</i> and <i>B</i>).
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Write a function that takes two arrays as parameters and returns the symmetric difference. Note: Sort the resultant array before returning it.
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</section>
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## Instructions
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<section id='instructions'>
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</section>
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## Tests
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<section id='tests'>
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``` yml
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tests:
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- text: <code>symmetricDifference</code> should be a function.
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testString: assert(typeof symmetricDifference == 'function', '<code>symmetricDifference</code> should be a function.');
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- text: <code>symmetricDifference(["John", "Bob", "Mary", "Serena"], ["Jim", "Mary", "John", "Bob"])</code> should return a array.
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testString: assert(Array.isArray(symmetricDifference(["John", "Bob", "Mary", "Serena"], ["Jim", "Mary", "John", "Bob"])), '<code>symmetricDifference(["John", "Bob", "Mary", "Serena"], ["Jim", "Mary", "John", "Bob"])</code> should return a array.');
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- text: <code>symmetricDifference(["John", "Bob", "Mary", "Serena"], ["Jim", "Mary", "John", "Bob"])</code> should return <code>["Jim", "Serena"]</code>.
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testString: assert.deepEqual(symmetricDifference(["John", "Bob", "Mary", "Serena"], ["Jim", "Mary", "John", "Bob"]), ["Jim", "Serena"], '<code>symmetricDifference(["John", "Bob", "Mary", "Serena"], ["Jim", "Mary", "John", "Bob"])</code> should return <code>["Jim", "Serena"]</code>.');
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- text: <code>symmetricDifference([1, 2, 3], [3, 4])</code> should return <code>[1, 2, 4]</code>.
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testString: assert.deepEqual(symmetricDifference([1, 2, 3], [3, 4]), [1, 2, 4], '<code>symmetricDifference([1, 2, 3], [3, 4])</code> should return <code>[1, 2, 4]</code>.');
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- text: <code>symmetricDifference([1, 2, 3, 4, 5], [3, 4, 8, 7])</code> should return <code>[1, 2, 5, 7, 8]</code>.
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testString: assert.deepEqual(symmetricDifference([1, 2, 3, 4, 5], [3, 4, 8, 7]), [1, 2, 5, 7, 8], '<code>symmetricDifference([1, 2, 3, 4, 5], [3, 4, 8, 7])</code> should return <code>[1, 2, 5, 7, 8]</code>.');
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- text: <code>symmetricDifference([1, 2, 3, 4, 5, 6, 7, 8], [1, 3, 5, 6, 7, 8, 9])</code> should return <code>[2, 4, 9]</code>.
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testString: assert.deepEqual(symmetricDifference([1, 2, 3, 4, 5, 6, 7, 8], [1, 3, 5, 6, 7, 8, 9]), [2, 4, 9], '<code>symmetricDifference([1, 2, 3, 4, 5, 6, 7, 8], [1, 3, 5, 6, 7, 8, 9])</code> should return <code>[2, 4, 9]</code>.');
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- text: <code>symmetricDifference([1, 2, 4, 7, 9], [2, 3, 7, 8, 9])</code> should return <code>[1, 3, 4, 8]</code>.
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testString: assert.deepEqual(symmetricDifference([1, 2, 4, 7, 9], [2, 3, 7, 8, 9]), [1, 3, 4, 8], '<code>symmetricDifference([1, 2, 4, 7, 9], [2, 3, 7, 8, 9])</code> should return <code>[1, 3, 4, 8]</code>.');
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```
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</section>
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## Challenge Seed
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<section id='challengeSeed'>
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<div id='js-seed'>
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```js
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function symmetricDifference (A, B) {
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// Good luck!
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}
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```
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</div>
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</section>
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## Solution
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<section id='solution'>
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```js
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function symmetricDifference (A, B) {
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function relative_complement(A, B) {
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return A.filter(function(elem) {
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return B.indexOf(elem) == -1
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});
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}
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function unique(ary) {
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var u = ary.concat().sort();
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for (var i = 1; i < u.length;) {
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if (u[i - 1] === u[i])
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u.splice(i, 1);
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else
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i++;
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}
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return u;
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}
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return unique(relative_complement(A, B).concat(relative_complement(B, A))).sort();
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}
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```
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</section> |