#!/usr/bin/env PyPy3

from collections import Counter, defaultdict, deque
import itertools
import re
import math
from functools import reduce
import operator
import bisect
import heapq
import functools
mod=10**9+7

import sys
input=sys.stdin.readline
t = int(input())
for _ in range(t):
    n=int(input())
    a=list(map(int,input().split()))
    a.sort()
    ans = 0
    l=0
    r=n-1
    cnt = 0
    while cnt < n:
        if cnt % 2 == 0:
            if cnt == n - 1:
                ans += a[l]
                cnt += 1
                continue
            if a[r] - a[r-1] + a[l] >= a[l+1]:
                ans += a[r] - a[r-1]
                r -= 1
            else:
                l += 1
        else:
            r -= 1
        cnt += 1
    print(ans)