public class Solution
extends Object
1497 - Check If Array Pairs Are Divisible by k\.
Medium
Given an array of integers `arr` of even length `n` and an integer `k`.
We want to divide the array into exactly `n / 2` pairs such that the sum of each pair is divisible by `k`.
Return `true` _If you can find a way to do that or_ `false` _otherwise_.
**Example 1:**
**Input:** arr = [1,2,3,4,5,10,6,7,8,9], k = 5
**Output:** true
**Explanation:** Pairs are (1,9),(2,8),(3,7),(4,6) and (5,10).
**Example 2:**
**Input:** arr = [1,2,3,4,5,6], k = 7
**Output:** true
**Explanation:** Pairs are (1,6),(2,5) and(3,4).
**Example 3:**
**Input:** arr = [1,2,3,4,5,6], k = 10
**Output:** false
**Explanation:** You can try all possible pairs to see that there is no way to divide arr into 3 pairs each with sum divisible by 10.
**Constraints:**
* `arr.length == n`
* 1 <= n <= 105
* `n` is even.
* -109 <= arr[i] <= 109
* 1 <= k <= 105