lightoj1005

CODE

#include <iostream>

using namespace std;
long long c(long long n,long long k)
{
        long long res = 1;
        for(int i=1;i<=k;i++)
        {
                res*=n-i+1;
                res/=i;
        }
        return res;
}
long long f[35];
int t,n,k;
int main()
{
        f[0]=1;
        for(int i=1;i<32;i++)
        {
                f[i]=f[i-1]*i;
        }
        cin >> t;
        for(int nCase =1;nCase <=t;nCase++)
        {
                cout << "Case "<<nCase<<": ";


       cin >> n >> k;
            cout << c(n,k)*c(n,k)*f[k]<<endl;

    }
    return 0;

}