1843A - Sasha and Array Coloring - CodeForces Solution

#include <bits/stdc++.h>
#include<string.h>

#define fastio() ios_base::sync_with_stdio(false);cin.tie(NULL);cout.tie(NULL)

#define YES cout<<"YES\n";
#define NO cout<<"NO\n";
#define all(v) v.begin(),v.end()
const int maxi=1e9;

using namespace std;
typedef long long ll;
typedef unsigned long long ull;
typedef long double lld;

#ifndef ONLINE_JUDGE
#define debug(x) cerr << #x <<" "; _print(x); cerr << endl;
#else
#define debug(x)
#endif

void _print(ll t) {cerr << t;}
void _print(int t) {cerr << t;}
void _print(string t) {cerr << t;}
void _print(char t) {cerr << t;}
void _print(lld t) {cerr << t;}
void _print(double t) {cerr << t;}
void _print(ull t) {cerr << t;}

template <class T, class V> void _print(pair <T, V> p);
template <class T> void _print(vector <T> v);
template <class T> void _print(set <T> v);
template <class T, class V> void _print(map <T, V> v);
template <class T> void _print(multiset <T> v);
template <class T, class V> void _print(pair <T, V> p) {cerr << "{"; _print(p.first); cerr << ","; _print(p.second); cerr << "}";}
template <class T> void _print(vector <T> v) {cerr << "[ "; for (T i : v) {_print(i); cerr << " ";} cerr << "]";}
template <class T> void _print(set <T> v) {cerr << "[ "; for (T i : v) {_print(i); cerr << " ";} cerr << "]";}
template <class T> void _print(multiset <T> v) {cerr << "[ "; for (T i : v) {_print(i); cerr << " ";} cerr << "]";}
template <class T, class V> void _print(map <T, V> v) {cerr << "[ "; for (auto i : v) {_print(i); cerr << " ";} cerr << "]";}

/*_________________________________________________________________________________________________________________________________*/

void solve()
{   
    ll n;
    cin>>n;

    vector<ll>v(n);
    for(ll i=0;i<n;i++)
        cin>>v[i];

    sort(all(v));

    ll cost = 0;

    for(ll i=0;i<n/2;i++)
        cost+=(v[n-1-i]-v[i]);
    

    cout<<cost<<"\n";
} 


int main()
{ 
    #ifndef ONLINE_JUDGE
        freopen("Error.txt", "w", stderr);
    #endif
    
    ll t;
    cin>>t;
    while(t--) 
        solve();
    
    return 0;  
}