79d9012432
* fix(curriculum): tests quotes * fix(curriculum): fill seed-teardown * fix(curriculum): fix tests and remove unneeded seed-teardown
109 lines
3.1 KiB
Markdown
109 lines
3.1 KiB
Markdown
---
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title: Combinations
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id: 5958469238c0d8d2632f46db
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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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Task:
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<p>Given non-negative integers <big> m </big> and <big> n</big>, generate all size <big> m </big> <a href="http://mathworld.wolfram.com/Combination.html" title="link: http://mathworld.wolfram.com/Combination.html">combinations</a> of the integers from <big> 0</big> (zero) to <big> n-1 </big> in sorted order (each combination is sorted and the entire table is sorted).</p>
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Example:
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<p><big>3</big> comb <big> 5 </big>is:</p>
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<pre>
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0 1 2
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0 1 3
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0 1 4
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0 2 3
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0 2 4
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0 3 4
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1 2 3
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1 2 4
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1 3 4
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2 3 4
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</pre>
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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>combinations</code> is a function.
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testString: assert(typeof combinations === 'function', '<code>combinations</code> is a function.');
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- text: <code>combinations(3, 5)</code> should return <code>[[0, 1, 2], [0, 1, 3], [0, 1, 4], [0, 2, 3], [0, 2, 4], [0, 3, 4], [1, 2, 3], [1, 2, 4], [1, 3, 4], [2, 3, 4]]</code>.
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testString: assert.deepEqual(combinations(testInput1[0], testInput1[1]), testOutput1, '<code>combinations(3, 5)</code> should return <code>[[0, 1, 2], [0, 1, 3], [0, 1, 4], [0, 2, 3], [0, 2, 4], [0, 3, 4], [1, 2, 3], [1, 2, 4], [1, 3, 4], [2, 3, 4]]</code>.');
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- text: <code>combinations(4, 6)</code> should return <code>[[0,1,2,3], [0,1,2,4], [0,1,2,5], [0,1,3,4], [0,1,3,5], [0,1,4,5], [0,2,3,4], [0,2,3,5], [0,2,4,5], [0,3,4,5], [1,2,3,4], [1,2,3,5], [1,2,4,5], [1,3,4,5], [2,3,4,5]]</code>
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testString: assert.deepEqual(combinations(testInput2[0], testInput2[1]), testOutput2, '<code>combinations(4, 6)</code> should return <code>[[0,1,2,3], [0,1,2,4], [0,1,2,5], [0,1,3,4], [0,1,3,5], [0,1,4,5], [0,2,3,4], [0,2,3,5], [0,2,4,5], [0,3,4,5], [1,2,3,4], [1,2,3,5], [1,2,4,5], [1,3,4,5], [2,3,4,5]]</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 combinations (m, n) {
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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 testInput1 = [3, 5];
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const testOutput1 = [[0, 1, 2], [0, 1, 3], [0, 1, 4], [0, 2, 3], [0, 2, 4], [0, 3, 4], [1, 2, 3], [1, 2, 4], [1, 3, 4], [2, 3, 4]];
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const testInput2 = [4, 6];
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const testOutput2 = [[0, 1, 2, 3], [0, 1, 2, 4], [0, 1, 2, 5], [0, 1, 3, 4], [0, 1, 3, 5], [0, 1, 4, 5], [0, 2, 3, 4], [0, 2, 3, 5], [0, 2, 4, 5], [0, 3, 4, 5], [1, 2, 3, 4], [1, 2, 3, 5], [1, 2, 4, 5], [1, 3, 4, 5], [2, 3, 4, 5]];
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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 combinations (m, n) {
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const nArr = [...Array(n).keys()];
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return (function generateCombinations (size, numArr) {
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const ret = [];
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for (let i = 0; i < numArr.length; i++) {
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if (size === 1) {
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ret.push([numArr[i]]);
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}
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else {
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const sub = generateCombinations(size - 1, numArr.slice(i + 1, numArr.length));
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for (let subI = 0; subI < sub.length; subI++) {
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const next = sub[subI];
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next.unshift(numArr[i]);
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ret.push(next);
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}
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}
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}
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return ret;
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}(m, nArr));
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}
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```
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</section>
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