/*
 *   Copyright (c) 2024 Emon Thakur
 *   All rights reserved.
 */
#include<bits/stdc++.h>
using namespace std;

void solve()
{
    int x,k,n; cin>>n>>k;
    map<int,int>m;
    for(int i=0;i<n;i++)
    {
        cin>>x;
        m[x]++;
    }
    priority_queue<int>pq;
    for(auto e:m) pq.push(e.second);
    
    int g = n/k;
    int r = n%k;
    int need = g+1;
    int ans = 0;
    for(int i=0;i<r;i++)
    {
        int tp = pq.top();
        pq.pop();
        ans += max(0,need-tp);
        tp = max(0,tp-need);
        if(tp>0) pq.push(tp);
    }
    need = g;
    for(int i=r;i<k;i++)
    {
        int tp = pq.top();
        pq.pop();
        ans += max(0,need-tp);
        tp = max(0,tp-need);
        if(tp>0) pq.push(tp);
    }
    cout<<ans<<endl;
}

int main()
{
    ios::sync_with_stdio(false); cin.tie(nullptr);
    int t; cin>>t; while(t--) solve();
}