Grokking the Coding Interview: Patterns for Coding Questions

Solution: Number Range

## Problem Statement

Given an array of numbers sorted in ascending order, find the range of a given number ‘key’. The range of the ‘key’ will be the first and last position of the ‘key’ in the array.

Write a function to return the range of the ‘key’. If the ‘key’ is not present return [-1, -1].

**Example 1**:
```
Input: [4, 6, 6, 6, 9], key = 6
Output: [1, 3]
```
**Example 2**:
```
Input: [1, 3, 8, 10, 15], key = 10
Output: [3, 3]
```
**Example 3**:
```
Input: [1, 3, 8, 10, 15], key = 12
Output: [-1, -1]
```

**Constraints:**

- 0 <= nums.length <= 10<sup>5</sup>