C++ :

#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <algorithm>
#include <string>
#include <map>
#include <iostream>
#include <cmath>
#include <vector>
using namespace std;
const int N = 1005;
const int mod=1e9+7;
int C[N+5][N+5],a[N+5];
void add(int &a, int b) {
a += b; if(a >= mod) a -= mod;
}
void init() {
C[0][0] = 1;
for(int i = 1; i <= N; i ++) {
C[i][0] = C[i][i] = 1;
for(int j = 1; j < i; j ++)
C[i][j] = C[i - 1][j - 1], add(C[i][j], C[i - 1][j]);
}
}
int main() {
// freopen("data/10.in", "r", stdin);
init();
int T;
scanf("%d", &T);
while(T --) {
int n,m,sum=0;
scanf("%d%d", &n, &m);
for(int i=1;i<=m;i++)
scanf("%d", &a[i]), sum += a[i];
int ans=1;
for(int i=1;i<=m;i++){
ans = 1ll * ans * C[sum][a[i]] % mod;
sum-=a[i];
}
cout<<ans<<endl;
}
return 0;
}