这就是AC代码😄

#include<bits/stdc++.h>
#define ll long long
using namespace std;
ll n,a[3000005],t=1;
int main(){
	cin>>n;
	for(int i=1;i<=n;i++){
		cin>>a[i];
	}
	sort(a+1,a+n+1);
	for(int i=1;i<=n;i++){
		t*=(a[i]-(i-1));
		t%=1000000007;
	}
	cout<<t;
	return 0;
}