import std.conv, std.functional, std.range, std.stdio, std.string;
import std.algorithm, std.array, std.bigint, std.bitmanip, std.complex, std.container, std.math, std.mathspecial, std.numeric, std.regex, std.typecons;
import core.bitop;

class EOFException : Throwable { this() { super("EOF"); } }
string[] tokens;
string readToken() { for (; tokens.empty; ) { if (stdin.eof) { throw new EOFException; } tokens = readln.split; } auto token = tokens.front; tokens.popFront; return token; }
int readInt() { return readToken.to!int; }
long readLong() { return readToken.to!long; }
real readReal() { return readToken.to!real; }

bool chmin(T)(ref T t, in T f) { if (t > f) { t = f; return true; } else { return false; } }
bool chmax(T)(ref T t, in T f) { if (t < f) { t = f; return true; } else { return false; } }

int binarySearch(alias pred, T)(in T[] as) { int lo = -1, hi = cast(int)(as.length); for (; lo + 1 < hi; ) { const mid = (lo + hi) >> 1; (unaryFun!pred(as[mid]) ? hi : lo) = mid; } return hi; }
int lowerBound(T)(in T[] as, T val) { return as.binarySearch!(a => (a >= val)); }
int upperBound(T)(in T[] as, T val) { return as.binarySearch!(a => (a > val)); }



void experimentUso() {
  foreach (n; 1 .. 6 + 1) {
    // want at least as good as p
    foreach (p; 0 .. 1 << n) {
      auto dp0 = new bool[][](1 << n, 1 << n);
      auto dp1 = new bool[][](1 << n, 1 << n);
      foreach (r; 0 .. 1 << n) {
        ((!(p & ~r)) ? dp1[0][r] : dp0[0][r]) = true;
      }
      foreach (q; 1 .. 1 << n) foreach (r; 0 .. 1 << n) {
        foreach (i; 0 .. n) if (q & 1 << i) {
          const qq = q ^ 1 << i;
          const move = (1 << (i + 1)) - 1;
          if (!dp1[qq][r & ~move]) dp0[q][r] = true;
          if (!dp0[qq][r | move]) dp1[q][r] = true;
        }
      }
      if (dp1[(1 << n) - 1][0]) {
        writeln(iota(n).map!(i => "01"[p >> i & 1]));
      }
    }
  }
}


enum INF = 10L^^18;

long brute(const(long[]) B) {
  const N = cast(int)(B.length);
  auto dp = new long[][](1 << N, 1 << N);
  foreach (i; 0 .. N) {
    foreach (r; 0 .. 1 << i) {
      dp[0][r | 1 << i] = dp[0][r] + B[i];
    }
  }
  foreach (q; 1 .. 1 << N) foreach (r; 0 .. 1 << N) {
    if ((N - popcnt(q)) % 2 == 0) {
      // 1
      dp[q][r] = -INF;
      foreach (i; 0 .. N) if (q & 1 << i) {
        chmax(dp[q][r], dp[q ^ 1 << i][r | ((1 << (i + 1)) - 1)]);
      }
    } else {
      // 0
      dp[q][r] = +INF;
      foreach (i; 0 .. N) if (q & 1 << i) {
        chmin(dp[q][r], dp[q ^ 1 << i][r & ~((1 << (i + 1)) - 1)]);
      }
    }
  }
  return dp[$ - 1][0];
}

long solve(const(long[]) B) {
  const N = cast(int)(B.length);
  long ans;
  if (N % 2 != 0) {
    ans += B[0];
    BinaryHeap!(Array!long) que;
    for (int i = 1; i < N; i += 2) {
      que.insert(B[i]);
      que.insert(B[i + 1]);
      ans += que.front;
      que.removeFront;
    }
  } else {
    ans += B[N - 1];
    BinaryHeap!(Array!long, "a > b") que;
    for (int i = N - 2; i > 0; i -= 2) {
      que.insert(B[i]);
      que.insert(B[i - 1]);
      ans += que.front;
      que.removeFront;
    }
  }
  return ans;
}

void experiment() {
  foreach (n; 1 .. 6 + 1) {
    auto bs = new long[n];
    foreach (i; 0 .. n) {
      bs[i] = 1 << i;
    }
    do {
      const brt = brute(bs);
      const sol = solve(bs);
      writeln(bs, ": ", iota(n).map!(i => ((brt & bs[i]) ? '1' : '0')), " ", brt, " ", sol);
      assert(popcnt(brt) == (n + 1) / 2);
      if (n % 2 != 0) {
        assert(brt == sol);
      } else {
        assert(brt & bs[n - 1]);
        assert(brt == sol);
      }
    } while (bs.nextPermutation);
  }
}

void main() {
  debug {
    experiment;
  }
  
  try {
    for (; ; ) {
      const numCases = readInt;
      foreach (caseId; 0 .. numCases) {
        const N = readInt;
        auto A = new long[N];
        foreach (i; 0 .. N) {
          A[i] = readLong;
        }
        A.sort;
        
        auto B = A.dup;
        foreach_reverse (i; 1 .. N) {
          B[i] -= B[i - 1];
        }
        
        const ans = solve(B);
        writeln(ans);
        
        debug {
          const brt = brute(B);
          writeln("B = ", B);
          writeln("brt = ", brt);
        }
      }
    }
  } catch (EOFException e) {
  }
}