function divisibleSumPairs(n, k, ar) {
    let pairCount = 0;
    let remainders = new Array(k).fill(0);
    
    for(let i = 0; i < n; i++){
        let num = ar[i];
        let remainder = num % k;
        let compliment = (k - remainder)% k;
        
        pairCount += remainders[compliment];
        remainders[remainder]++;
    }
    return pairCount;
}