JAVA Solution

public static int divisibleSumPairs(int n, int k, List ar) {

    int count = 0;

    for(int i = 0; i<n; i++){

        for(int j = i+1; j<n; j++){

            if((ar.get(i)+ ar.get(j)) % k == 0){
                count++;
            }
        }
    }

    return count;

}