Divisible Sum Pairs hackerank solution
import java.io.*;
import java.util.*;
import java.text.*;
import java.math.*;
import java.util.regex.*;
public class Solution {
public static void main(String[] args) {
Scanner in = new Scanner(System.in);
int n = in.nextInt();
int k = in.nextInt();
int a[] = new int[n];
for(int a_i=0; a_i < n; a_i++){
a[a_i] = in.nextInt();
}
int cnt=0;
for (int i = 0 ;i<n-1;i++) {
for (int j=i+1;j<n;j++) {
if ((a[i]+a[j]) % k == 0)
cnt ++;
}
}
System.out.println(cnt);
}
}