#include <stdio.h>
#include <algorithm>
#include <iostream>
#include <map>
#include <stack>
#include <vector>
#include <memory.h>
#include <set>
#include <string.h>
#include <list>
#include <string>
#include <math.h>
#include <stdlib.h>
#include <queue>
#include <time.h>
#define ll long long
#define forn(i,n) for(int i=0;i<n;++i)
#define rep(i,n) for(int i=1;i<=n;++i)
#define repc(i,l,r) for(int i=l;i<=r;++i)
#define mp(a,b) make_pair(a,b)
#define llf long double
#define pii pair<int,int>
using namespace std;
int s[100005];
int n;
ll f[100005];
ll g[100005];
void solve(){
    cin >> n;
    forn(i, n)scanf("%d", s + i);
    sort(s, s + n);
    f[0] = g[0] = 0;
    rep(i, n){
        f[i] = max(f[i - 1], g[i - 1] + s[i-1]);
        g[i] = min(g[i - 1], f[i - 1] - s[i-1]);
    }
    cout << f[n] << endl;
}
int main(){
//freopen("abc.txt", "r", stdin);
    int T;
    cin >> T;
    while (T--){
        solve();
    }
    return 0;
}