#include <bits/stdc++.h>

#define endl "\n"
#define int long long
using namespace std;

typedef pair<int,int> PII;
const int N = 2e5 + 5, MOD = 1e9 + 7;
int n;
int a[N];

int fac[N],inv[N];

int ksm(int a,int b){
    int r = 1;
    while (b){
        if (b & 1) r = r * a % MOD;
        a = a * a % MOD;
        b >>= 1;
    }
    return r;
}

void init(){
    fac[0] = 1;
    for (int i = 1;i < N;i ++){
        fac[i] = fac[i - 1] * i % MOD;
    }
    inv[N - 1] = ksm(fac[N - 1], MOD - 2);
    for (int i = N - 2; i >= 0; i--){
        inv[i] = inv[i + 1] * (i + 1) % MOD;
    }
}
int C(int n,int m){
    if (m > n) return 0;
    if (m == 0) return 1;
    return fac[n] * inv[m] % MOD * inv[n - m] % MOD;
}

int A(int n,int m){
    if (m > n) return 0;
    if (m == 0) return 1;
    return fac[n] * inv[n - m] % MOD;
}

void solve(){
    cin >> n;
    bool f = 0;
    for(int i = 1; i <= n; i++){
        cin >> a[i];
    }
    if(a[1] != 0 || a[n] != n - 1){
        cout << 0 << endl;
        return;
    }
    int cnt = 0;
    for(int i = 2; i <= n; i++){
        if(a[i] != a[i - 1]) cnt++;
        if(a[i] + 1 < i){
            cout << 0 << endl;
            return;
        }
    }
    cout << (n - a[2]) * 2 * fac[n - 1 - cnt] << endl;
}

signed main(){
    ios::sync_with_stdio(false);
    cin.tie(nullptr);
    init();
    int _ = 1;
    cin >> _;
    while(_--){
        solve();
    }
}