LeetCode 1497. Check If Array Pairs Are Divisible by k

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总不过，真的想不出来是什么原因，因为是在数据集很大的时候不过的，

没办法就换成数组了，秒过。。。。

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.