#include<iostream>
#include<cstdio>
#include<cstring>
#include<cstdlib>
#include<cmath>
#include<algorithm>
#define ll long long
#define mod 1000000007
using namespace std;

int n,a[1000005];
ll solve(){
    int i; ll ans=26;
    for (i=1; i<n; i++) scanf("%d",&a[i]); a[n]=0;
    for (i=n-1; i; i--){
        if (!a[i]) ans=ans*25%1000000007;
            else if (a[i]!=a[i+1]+1) return 0;
    }
    return ans;
}
int main(){
    int cas; scanf("%d",&cas);
    while (cas--){
        scanf("%d",&n);
        printf("%I64d\n",solve());
    }
    return 0;
}