Codechef_problem/Maximum_Alternating_Sum.cpp at main · aroyy007/Codechef_problem · GitHub

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#include <iostream>

#include <bits/stdc++.h>

#include <algorithm>

#include <vector>

#include <stdlib.h>

#include <time.h>

using namespace std;
#define optimize()\
ios_base::sync_with_stdio(0);\
cin.tie(0);\
cout.tie(0);
#define fraction()\
cout.unsetf(ios::floatfield);\
cout.precision(10);\
cout.setf(ios::fixed, ios::floatfield);
#define file()\
freopen("input.txt", "r", stdin);\
freopen("output.txt", "w", stdout);

typedef long long ll;
typedef vector < int > vi;
typedef vector < ll > vl;
typedef vector < vi > vvi;
typedef vector < vl > vvl;
typedef pair < int, int > pii;
typedef pair < double, double > pdd;
typedef pair < ll, ll > pll;
typedef vector < pii > vii;
typedef vector < pll > vll;
typedef double dl;
#define endl '\n'
#define PB push_back
#define coy cout << "YES" << endl;
#define con cout << "NO" << endl;
#define ain(A, NN)\
for (ll I = 0; I < NN; I++)\
    cin >> A[I]
using namespace std;

int main()
{
    optimize();

    ll t;
    cin >> t;
    while (t--)
    {
        ll n;
        cin >> n;

        vector < ll > a(n);
        ain(a, n);

        sort(a.begin(), a.end());
        //reverse(a.begin(), a.end());

        ll sum1 = 0, sum2 = 0;

        for (int i = 0; i < n; i++)
        {
            if (i < (n / 2))
            {
                sum1 += a[i];
            }
            else
            {
                sum2 += a[i];
            }
        }

        cout << sum2-sum1 << endl;
    }

    return 0;
}