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#include <bits/stdc++.h>
using namespace std;

typedef long long int lli;

lli MOD = 1000000007;
const int MAXN = 4000025;

lli fac[MAXN];
lli ip2[MAXN];

lli pot(lli a, lli n) {
	assert(n >= 0);
	if (n == 0)
		return 1;
	if (n % 2 == 0)
		return pot((a*a)%MOD, n/2);
	else
		return (a*pot(a, n-1))%MOD;
}

lli inv(lli a) {
	return pot(a, MOD-2);
}

lli binom(lli n, lli k) {
	if (n < 0 || k < 0 || k > n)
		return 0;
	return (fac[n] * inv((fac[k] * fac[n-k]) % MOD))%MOD;
}

void answer(lli a) {
	printf("%lld\n", a);
}

void solve() {
	int n;
	vector<int> v;
	scanf("%d", &n);
	
	int cnt[3];
	for (int i=0; i<3; i++)
		cnt[i] = 0;
	
	for (int i=0; i<2*n; i++) {
		int a;
		scanf("%d", &a);
		v.push_back(a);
		cnt[a]++;
	}
	
	if (cnt[0] > 0 && cnt[2] > 0)
		return answer(0);
	
	if (cnt[1] == 2*n) {
		lli ans = binom(4*n-3, 2*n-1);
		for (int i=1; i<=n; i++) {
			lli b = binom(2*i, 2);
			ans = (ans * (b*b)%MOD)%MOD;
		}
		return answer((ans*2)%MOD);
	}
	
	if (cnt[0] == 2*n || cnt[2] == 2*n) {
		lli ans = binom(4*n-2, 2*n-2);
		for (int i=1; i<=n; i++) {
			lli b = binom(2*i, 2);
			ans = (ans * (b*b)%MOD)%MOD;
		}
		return answer(ans);
	}
	
	// convert to 0/1
	if (cnt[2] > 0) {
		vector<int> tmp_v;
		tmp_v.push_back(2 - v.back());
		for (int i=0; i<(int)v.size()-1; i++) {
			tmp_v.push_back(2 - v[i]);
		}
		v.swap(tmp_v);
	}
	
// 	for (int i=0; i<2*n; i++)
// 		printf(" %d", v[i]);
// 	printf("\n");
	
	
	for (int i=0; i<2*n; i++)
		v.push_back(v[i]);
	
	int beg = 1;
	while (v[beg-1] == v[beg])
		beg++;
	int master_beg = beg;
// 	printf("master beg: %d\n", master_beg);
	
	if (v[master_beg] == master_beg%2)
		return answer(0);
	
	vector<int> ints;
	
	while (beg < master_beg + 2*n) {
		for (int i=beg; true; i++) {
			if (v[i] != v[beg]) {
				if ((i-1)%2 != beg%2)
					return answer(0);
				ints.push_back(i - beg);
				beg = i;
				break;
			}
		}
	}
	
	lli ic = ints.size();
	assert(ic%2 == 0);
	
	lli res = 0;
	
	beg = 0;
	if (v[master_beg] == 0) {
		beg = 1;
		ints.push_back(ints[0]);
	}
	
// 	for (int i=0; i<(int)ints.size(); i++)
// 		printf(" %d", ints[i]);
// 	printf(" (ints)\n");
	
// 	lli B = 1;
// 	for (int i=1; i<=n; i++) {
// 		lli b = binom(2*i, 2);
// 		B = (B * b)%MOD;
// 	}
// 	B = (B*B)%MOD;


        // l-1
		// case 2
		lli a_x = binom(4*n-ic-2, 2*n-ic/2);
		lli mul1_x = (fac[2*n-ic/2] * inv(pot(2, n-ic/2)))%MOD;
		lli mul2_x = (fac[2*n-ic/2] * inv(pot(2, n-ic/2)))%MOD;
		lli mul_x = (mul1_x * mul2_x) % MOD;
		
		// case 1
		lli a_z = binom(4*n-ic-2, 2*n-ic/2-1);
		lli mul1_z = (fac[2*n-ic/2] * inv(pot(2, n-ic/2)))%MOD;
		a_z = (a_z * mul1_z) % MOD;
		// fixed 1
		lli mul21_z = ((ic/2) * fac[2*n-ic/2-1])%MOD;
		mul21_z = (mul21_z * inv(pot(2, n-ic/2)))%MOD;
	
	// l-other
	lli a_y=0, mul1_y=0, mul2_y=0, mul_y=0, a_w=0, mul1_w=0, mul21_w=0;
	if (ic < 2*n) {
		// case 2
		a_y = binom(4*n-ic-3, 2*n-ic/2-1);
		mul1_y = (fac[2*n-ic/2-1] * inv(pot(2, n-ic/2-1)))%MOD;
		mul2_y = (fac[2*n-ic/2] * inv(pot(2, n-ic/2)))%MOD;
		mul_y = (mul1_y * mul2_y) % MOD;
		
		a_w = binom(4*n-ic-3, 2*n-ic/2-1);
		mul1_w = (fac[2*n-ic/2-1] * inv(pot(2, n-ic/2-1)))%MOD;
		a_w = (a_w * mul1_w) % MOD;
		// fixed 1
		mul21_w = ((ic/2) * fac[2*n-ic/2-1])%MOD;
		mul21_w = (mul21_w * inv(pot(2, n-ic/2)))%MOD;
	}
	
	for (int it=beg; it<(int)ints.size(); it+=2) {
		lli l = ints[it];
		lli next_l = ints[it+1];
		
// 		for (int i=0; i<l; i+=2) {
// 			if (i == l-1) {
// 				// case 2
// 				lli a = binom(4*n-ic-2, 2*n-ic/2);
// 				lli mul1 = (fac[2*n-ic/2] * inv(pot(2, n-ic/2)))%MOD;
// 				lli mul2 = (fac[2*n-ic/2] * inv(pot(2, n-ic/2)))%MOD;
// 				lli mul = (mul1 * mul2) % MOD;
// 				res = (res + a*mul)%MOD;
// 				
// 				// case 1
// 				a = binom(4*n-ic-2, 2*n-ic/2-1);
// 				mul1 = (fac[2*n-ic/2] * inv(pot(2, n-ic/2)))%MOD;
// 				a = (a * mul1) % MOD;
// 				// fixed 1
// 				lli mul21 = ((ic/2) * fac[2*n-ic/2-1])%MOD;
// 				mul21 = (mul21 * inv(pot(2, n-ic/2)))%MOD;
// 				// non-fixed 1
// 				lli mul22 = (n-ic/2-(next_l-1)/2)%MOD;
// 				if (mul22 != 0) {
// 					mul22 = (mul22 * fac[2*n-ic/2-1])%MOD;
// 					mul22 = (mul22 * inv(pot(2, n-ic/2-1)))%MOD;
// 				}
// 				
// 				res = (res + a*(mul21+mul22)) % MOD;
// 			}
// 			else {
// 				// case 2
// 				lli a = binom(4*n-ic-3, 2*n-ic/2-1);
// 				lli mul1 = (fac[2*n-ic/2-1] * inv(pot(2, n-ic/2-1)))%MOD;
// 				lli mul2 = (fac[2*n-ic/2] * inv(pot(2, n-ic/2)))%MOD;
// 				lli mul = (mul1 * mul2) % MOD;
// 				res = (res + a*mul)%MOD;
// 				
// 				a = binom(4*n-ic-3, 2*n-ic/2-1);
// 				mul1 = (fac[2*n-ic/2-1] * inv(pot(2, n-ic/2-1)))%MOD;
// 				a = (a * mul1) % MOD;
// 				// fixed 1
// 				lli mul21 = ((ic/2) * fac[2*n-ic/2-1])%MOD;
// 				mul21 = (mul21 * inv(pot(2, n-ic/2)))%MOD;
// 				// non-fixed 1
// 				lli mul22 = (n-ic/2-(l-i-1)/2)%MOD;
// 				if (mul22 != 0) {
// 					mul22 = (mul22 * fac[2*n-ic/2-1])%MOD;
// 					mul22 = (mul22 * inv(pot(2, n-ic/2-1)))%MOD;
// 				}
// 				
// 				res = (res + a*(mul21+mul22)) % MOD;
// 			}
// 		}
		
		
		for (int i=0; i<l; i+=2) {
			if (i == l-1) {
				res = (res + a_x*mul_x)%MOD;
				
				// non-fixed 1
				lli mul22_z = (n-ic/2-(next_l-1)/2)%MOD;  // next_l -> only variable
				if (mul22_z != 0) {
					mul22_z = (mul22_z * fac[2*n-ic/2-1])%MOD;
					mul22_z = (mul22_z * ip2[n-ic/2-1])%MOD;
				}
				
				res = (res + a_z*(mul21_z+mul22_z)) % MOD;
			}
			else {
				res = (res + a_y*mul_y)%MOD;
				
				// non-fixed 1
				lli mul22_w = (n-ic/2-(l-i-1)/2)%MOD;  // l-i -> only variable
				if (mul22_w != 0) {
					mul22_w = (mul22_w * fac[2*n-ic/2-1])%MOD;
					mul22_w = (mul22_w * ip2[n-ic/2-1])%MOD;
				}
				
				res = (res + a_w*(mul21_w+mul22_w)) % MOD;
			}
		}
	}
	
	printf("%lld\n", res);
}

int main() {
	fac[0] = 1;
	for (int i=1; i<MAXN-5; i++) {
		fac[i] = (fac[i-1] * i) % MOD;
	}
	
	ip2[0] = 1;
	ip2[1] = inv(2);
	for (int i=2; i<MAXN-5; i++) {
		ip2[i] = (ip2[i-1]*ip2[1])%MOD;
	}
	
	int T;
	scanf("%d", &T);
	
	while (T--)
		solve();
	
	return 0;
}