逆序数

#include 
#include 
#include 
#include 
#include 
#include 
#include 
using namespace std;
typedef long long ll;
int main()
{
    ll t,n,m;
    cin>>t;
    while(t--)
    {
        ll ans=0;
        scanf("%lld%lld",&n,&m);

            int z=min(m,(n/2));
            ans=2*z*(n-z-1)+z;
            printf("%lld\n",ans);

    }
    return 0;
}