iven 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

我用hashmap總不過，真的想不出來是什么原因，因?yàn)槭窃跀?shù)據(jù)集很大的時(shí)候不過的，

沒辦法就換成數(shù)組了，秒過。。。。

Runtime:?5 ms, faster than?96.99%?of?Java?online submissions for?Check If Array Pairs Are Divisible by k.

Memory Usage:?50.3 MB, less than?85.24%?of?Java?online submissions for?Check If Array Pairs Are Divisible by k.