95 lines
2.9 KiB
Markdown
95 lines
2.9 KiB
Markdown
---
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id: 5a23c84252665b21eecc802a
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title: Stream Merge
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challengeType: 5
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isHidden: false
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forumTopicId: 302326
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---
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## Description
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<section id='description'>
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Write a function that takes multiple sorted arrays of items, and returns one array of sorted items.
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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>mergeLists</code> should be a function.
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testString: assert(typeof mergeLists == 'function');
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- text: <code>mergeLists([[1, 3, 5, 9, 10], [2, 4, 6, 7, 8]])</code> should return an array.
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testString: assert(Array.isArray(mergeLists([[1, 3, 5, 9, 10], [2, 4, 6, 7, 8]])));
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- text: <code>mergeLists([[1, 3, 5, 9, 10], [2, 4, 6, 7, 8]])</code> should return <code>[1, 2, 3, 4, 5, 6, 7, 8, 9, 10]</code>.
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testString: assert.deepEqual(mergeLists([[1, 3, 5, 9, 10], [2, 4, 6, 7, 8]]), [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]);
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- text: <code>mergeLists([[1, 4, 7, 10], [2, 5, 8, 11], [3, 6, 9, 12]])</code> should return <code>[1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12]</code>.
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testString: assert.deepEqual(mergeLists([[1, 4, 7, 10], [2, 5, 8, 11], [3, 6, 9, 12]]), [1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12]);
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- text: <code>mergeLists([[1, 3, 9, 14, 15, 17, 28], [7, 8, 14, 14, 23, 26, 28, 29, 30], [9, 23, 25, 29]])</code> should return <code>[1, 3, 7, 8, 9, 9, 14, 14, 14, 15, 17, 23, 23, 25, 26, 28, 28, 29, 29, 30]</code>.
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testString: assert.deepEqual(mergeLists([[1, 3, 9, 14, 15, 17, 28], [7, 8, 14, 14, 23, 26, 28, 29, 30], [9, 23, 25, 29]]), [1, 3, 7, 8, 9, 9, 14, 14, 14, 15, 17, 23, 23, 25, 26, 28, 28, 29, 29, 30]);
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- text: <code>mergeLists([[3, 14, 15], [2, 17, 18], [], [2, 3, 5, 7]])</code> should return <code>[2, 2, 3, 3, 5, 7, 14, 15, 17, 18]</code>.
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testString: assert.deepEqual(mergeLists([[3, 14, 15], [2, 17, 18], [], [2, 3, 5, 7]]), [2, 2, 3, 3, 5, 7, 14, 15, 17, 18]);
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- text: <code>mergeLists([[1, 19, 1999], [17, 33, 2999, 3000], [8, 500, 3999]])</code> should return <code>[1, 8, 17, 19, 33, 500, 1999, 2999, 3000, 3999]</code>.
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testString: assert.deepEqual(mergeLists([[1, 19, 1999], [17, 33, 2999, 3000], [8, 500, 3999]]), [1, 8, 17, 19, 33, 500, 1999, 2999, 3000, 3999]);
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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 mergeLists(lists) {
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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 mergeLists(lists) {
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function merge(l1, l2) {
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var result = [],
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i = 0,
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j = 0;
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while (l1.length && l2.length) {
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if (l1[i] <= l2[j]) {
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result.push(l1.shift());
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} else {
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result.push(l2.shift());
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}
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}
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result.push.apply(result, l1);
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result.push.apply(result, l2);
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return result;
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}
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var result = lists[0];
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for (var i = 1; i < lists.length; i++) {
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result = merge(result, lists[i]);
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}
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return result;
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}
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```
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</section>
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