codeforces - zero reminder array

#include<bits/stdc++.h>
using namespace std;

#define ll long long
#define fast()(ios_base::sync_with_stdio(0),cin.tie(NULL));
#define pi pair<int , int>
#define mp make_pair
#define f first
#define s second

int main()
{
    ll t;
    cin>>t;
    while(t--)
    {
        ll n,k,mx=0;
        cin>>n>>k;
        map<ll,ll>mp;
        queue<ll>q;
        ll ara[n+1];
        for(ll i=0; i<n; i++)
        {
            cin>>ara[i];

        }
        sort(ara,ara+n);
        for(ll i=0; i<n; i++)
        {
            ll x=k-(ara[i]%k);
            if(x==k)continue;
            else
            {
                mp[x]++;
                q.push(x);
            }
        }
        while(!q.empty())
        {
            ll x= q.front();
            if(mp[x]>1)
            {
                mp[x]--;
                ll y=mp[x]*k+x;
                mx=max(mx,y);
                mp[y]++;
                q.push(y);
                q.pop();
            }
            else
            {
                mx=max(mx,x);
                q.pop();
            }
        }
        if(mx>0)mx++;
        cout<<mx<<endl;
    }

}