1827A - Counting Orders - CodeForces Solution

#include <bits/stdc++.h>
using namespace std;
long long N=1e9+7;
int main()
{
	int t;
	cin >> t;
	while (t--)
	{
		int n;

		cin >> n;
		int a[n], b[n];
		for (int i = 0; i < n; i++)
		{
			cin >> a[i];
		}
		for (int i = 0; i < n; i++)
		{
			cin >> b[i];
		}

		sort(a, a + n, greater<int>());
		sort(b, b + n, greater<int>());
		long long  j=0,count=0,ans=1;
		for (int i = 0; i < n; i++)
		{
             

			while(b[i]<a[j] and j<n){
				count++;
				 
				j++;
			}
           ans=(ans*(count-i)%N)%N;
			
		}
cout<<  ans<<endl;
	}

	return 0;
}