139 lines
4.7 KiB
Markdown
139 lines
4.7 KiB
Markdown
---
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title: Balanced brackets
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id: 594dc6c729e5700999302b45
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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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Determine whether a generated string of brackets is balanced; that is, whether it consists entirely of pairs of opening/closing brackets (in that order), none of which mis-nest.
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<h4><strong>Examples:</strong></h4>
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| Input | Output |
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| --- | --- |
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| <code>[]</code> | true |
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| <code>][</code> | false |
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| <code>[][]</code> | true |
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| <code>][][</code> | false |
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| <code>[]][[]</code> | false |
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| <code>[[[[]]]]</code> | true |
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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>isBalanced</code> is a function.
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testString: assert(typeof isBalanced === 'function', '<code>isBalanced</code> is a function.');
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- text: <code>isBalanced("[]")</code> should return true.
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testString: assert(isBalanced(testCases[0]), '<code>isBalanced("[]")</code> should return true.');
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- text: <code>isBalanced("]][[[][][][]][")</code> should return false.
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testString: assert(!isBalanced(testCases[1]), '<code>isBalanced("]][[[][][][]][")</code> should return false.');
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- text: <code>isBalanced("[][[[[][][[[]]]]]]")</code> should return true.
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testString: assert(isBalanced(testCases[2]), '<code>isBalanced("[][[[[][][[[]]]]]]")</code> should return true.');
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- text: <code>isBalanced("][")</code> should return true.
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testString: assert(!isBalanced(testCases[3]), '<code>isBalanced("][")</code> should return true.');
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- text: <code>isBalanced("[[[]]]][[]")</code> should return true.
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testString: assert(!isBalanced(testCases[4]), '<code>isBalanced("[[[]]]][[]")</code> should return true.');
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- text: <code>isBalanced("][[]")</code> should return true.
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testString: assert(!isBalanced(testCases[5]), '<code>isBalanced("][[]")</code> should return true.');
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- text: <code>isBalanced("][[][]][[[]]")</code> should return true.
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testString: assert(!isBalanced(testCases[6]), '<code>isBalanced("][[][]][[[]]")</code> should return true.');
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- text: <code>isBalanced("[[][]]][")</code> should return true.
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testString: assert(!isBalanced(testCases[7]), '<code>isBalanced("[[][]]][")</code> should return true.');
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- text: <code>isBalanced("[[[]]][[]]]][][[")</code> should return true.
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testString: assert(!isBalanced(testCases[8]), '<code>isBalanced("[[[]]][[]]]][][[")</code> should return true.');
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- text: <code>isBalanced("[]][[]]][[[[][]]")</code> should return true.
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testString: assert(!isBalanced(testCases[9]), '<code>isBalanced("[]][[]]][[[[][]]")</code> should return true.');
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- text: <code>isBalanced("][]][[][")</code> should return true.
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testString: assert(!isBalanced(testCases[10]), '<code>isBalanced("][]][[][")</code> should return true.');
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- text: <code>isBalanced("[[]][[][]]")</code> should return true.
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testString: assert(isBalanced(testCases[11]), '<code>isBalanced("[[]][[][]]")</code> should return true.');
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- text: <code>isBalanced("[[]]")</code> should return true.
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testString: assert(isBalanced(testCases[12]), '<code>isBalanced("[[]]")</code> should return true.');
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- text: <code>isBalanced("]][]][[]][[[")</code> should return true.
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testString: assert(!isBalanced(testCases[13]), '<code>isBalanced("]][]][[]][[[")</code> should return true.');
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- text: <code>isBalanced("][]][][[")</code> should return true.
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testString: assert(!isBalanced(testCases[14]), '<code>isBalanced("][]][][[")</code> should return true.');
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- text: <code>isBalanced("][][")</code> should return true.
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testString: assert(!isBalanced(testCases[15]), '<code>isBalanced("][][")</code> should return true.');
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- text: <code>isBalanced("[[]]][][][[]][")</code> should return true.
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testString: assert(!isBalanced(testCases[16]), '<code>isBalanced("[[]]][][][[]][")</code> should return true.');
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- text: <code>isBalanced("")</code> should return true.
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testString: assert(isBalanced(testCases[17]), '<code>isBalanced("")</code> should return true.');
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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 isBalanced(str) {
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// Good luck!
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return true;
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}
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```
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</div>
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### After Test
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<div id='js-teardown'>
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```js
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const testCases = [
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'[]',
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']][[[][][][]][',
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'[][[[[][][[[]]]]]]',
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'][',
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'[[[]]]][[]',
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'][[]',
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'][[][]][[[]]',
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'[[][]]][',
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'[[[]]][[]]]][][[',
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'[]][[]]][[[[][]]',
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'][]][[][',
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'[[]][[][]]',
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'[[]]',
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']][]][[]][[[',
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'][]][][[',
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'][][',
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'[[]]][][][[]][',
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''
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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 isBalanced(str) {
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if (str === '') return true;
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let a = str;
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let b;
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do {
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b = a;
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a = a.replace(/\[\]/g, '');
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} while (a !== b);
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return !a;
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}
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```
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</section>
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