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