Pattern Locker

求 C（n*n,l）l!+C(n*n,l+1)(l+1)!…..+C(n*n,r)*r!

#include <iostream>using namespace std;#include <stdio.h>#include <math.h>const long long mo = 10000000000007;long long n, l, r;int main() {    int tt;    cin >> tt;    long long ans, t;    for (int cases = 1; cases <= tt; cases++) {        cin >> n >> l >> r;        t = 1;        ans = 0;        for (int i = 1; i <= r; i++) {            t = (t*(n*n-i+1))%mo;            if (i >= l) ans = (ans+t)%mo;        }        cout << "Case " << cases << ": " << ans << endl;    }}