25 lines
708 B
Markdown
25 lines
708 B
Markdown
---
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title: sortedIndex
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tags: array,math,intermediate
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firstSeen: 2017-12-31T16:39:06+02:00
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lastUpdated: 2020-10-22T20:24:30+03:00
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---
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Finds the lowest index at which a value should be inserted into an array in order to maintain its sorting order.
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- Loosely check if the array is sorted in descending order.
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- Use `Array.prototype.findIndex()` to find the appropriate index where the element should be inserted.
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```js
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const sortedIndex = (arr, n) => {
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const isDescending = arr[0] > arr[arr.length - 1];
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const index = arr.findIndex(el => (isDescending ? n >= el : n <= el));
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return index === -1 ? arr.length : index;
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};
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```
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```js
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sortedIndex([5, 3, 2, 1], 4); // 1
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sortedIndex([30, 50], 40); // 1
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```
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