# 0954. Array of Doubled Pairs

https://leetcode.com/problems/array-of-doubled-pairs

## Description

Given an integer array of even length `arr`, return `true` _if it is possible to reorder_ `arr` _such that_ `arr[2 * i + 1] = 2 * arr[2 * i]` _for every_ `0 <= i < len(arr) / 2`_, or_ `false` _otherwise_.

**Example 1:**

```
**Input:** arr = [3,1,3,6]
**Output:** false
```

**Example 2:**

```
**Input:** arr = [2,1,2,6]
**Output:** false
```

**Example 3:**

```
**Input:** arr = [4,-2,2,-4]
**Output:** true
**Explanation:** We can take two groups, [-2,-4] and [2,4] to form [-2,-4,2,4] or [2,4,-2,-4].
```

**Example 4:**

```
**Input:** arr = [1,2,4,16,8,4]
**Output:** false
```

**Constraints:**

* `2 <= arr.length <= 3 * 104`
* `arr.length` is even.
* `-105 <= arr[i] <= 105`

## ac

```java
```
