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#define DEBUG
#include <algorithm>
#include <iostream>
#include <unordered_set>
#include <vector>
#ifdef DEBUG
#include <iomanip>
#endif

const long MOD = 1000000007;
const int MAX = 1000005;

// copy from https://cp-algorithms.com/algebra/module-inverse.html
long inv(long a) {
  return a <= 1 ? a : MOD - (long)(MOD / a) * inv(MOD % a) % MOD;
}

long F[MAX * 4];
long iF[MAX * 4];

void init() {
  F[0] = 1;
  for (long i = 1; i < MAX * 4; ++i) F[i] = F[i - 1] * i % MOD;
  // for (long i = 1; i < MAX * 4; ++i) iF[i] = inv(F[i]);
}

long C(long k, long n) { return F[n] * inv(F[k]) % MOD * inv(F[n - k]) % MOD; }

long pow(long a, long n) {
  long result = 1;
  while (n > 0) {
    if (n & 1) result = result * a % MOD;
    a = a * a % MOD;
    n >>= 1;
  }
  return result;
}

long zeros(long n) {
  return C(2 * n - 2, 4 * n - 2) * F[2 * n] % MOD * F[2 * n] % MOD *
         inv(pow(4, n)) % MOD;
}

long ones(long n) {
  return C(2 * n - 1, 4 * n - 3) * F[2 * n] % MOD * F[2 * n] % MOD *
         inv(pow(4, n)) % MOD * 2 % MOD;
}

long solve2(long segments, long ones, long n) {
  // std::clog << segments << " / " << ones << std::endl;

  long seq = ones * 2 + 2;
  long winner = ones;
  long tier = ones;

  if (ones % 2 == 0) {
    if (ones == n)
      winner += 1;
    else
      winner += 2;
  } else
    tier += 2;

  long random_winner = 2 * n - winner;
  long random_tier = 2 * n - tier;
  // std::clog << "random_winner " << random_winner << " " << random_tier
  //           << std::endl;

  long all = 4 * n;

  return ones * ones % MOD * F[random_winner + random_tier] % MOD;
}

int A[MAX * 2];

void solve() {
  long n;
  std::cin >> n;
  bool allzeros = true;
  bool allones = true;
  bool alltwos = true;
  bool anyzero = false;
  bool anytwo = false;
  int count = 0;
  int count_ones = 0;
  int parity = -1;
  std::unordered_set<int> one_parity;
  std::unordered_set<int> zero_parity;
  for (int i = 0; i < 2 * n; ++i) {
    std::cin >> A[i];
    anyzero |= A[i] == 0;
    anytwo |= A[i] == 2;
    allzeros &= A[i] == 0;
    allones &= A[i] == 1;
    alltwos &= A[i] == 2;
    if (i > 0 && A[i] != A[i - 1]) {
      if (A[i - 1] == 1) {
        ++count_ones;
        one_parity.insert((i - 1) % 2);
      } else
        zero_parity.insert((i - 1) % 2);
      ++count;
    }
  }
  if (A[2 * n - 1] != A[0]) {
    if (A[2 * n - 1] == 1) {
      ++count_ones;
      one_parity.insert((2 * n - 1) % 2);
    } else
      zero_parity.insert((2 * n - 1) % 2);
    ++count;
  }
  bool broken_parity = one_parity.size() > 1 || zero_parity.size() > 1 ||
                       !one_parity.empty() && !zero_parity.empty() &&
                           *one_parity.begin() == *zero_parity.begin();
  // std::clog << "P: " << one_parity.size() << " " << zero_parity.size()
  //           << std::endl;
  // if (broken_parity) std::clog << "broken_parity" << std::endl;
  if (allzeros || alltwos)
    std::cout << zeros(n) << std::endl;
  else if (allones)
    std::cout << ones(n) << std::endl;
  else if (anytwo && anyzero || broken_parity)
    std::cout << 0 << std::endl;
  else
    std::cout << solve2(count, count_ones, n) << std::endl;
}

int main() {
  std::ios_base::sync_with_stdio(0);
  init();
  int t;
  std::cin >> t;
  while (t--) solve();
  return 0;
}