hdu 6090

思路：菊花状的图。。。注意边大于构成完全图的情况

#include<bits/stdc++.h>
typedef long long ll;
using namespace std;

int main(){
    int t;
    scanf("%d",&t);
    while(t--){
        ll n,m;
        scanf("%lld%lld",&n,&m);
        ll sum=0;
        if(m>=n-1){
            sum+=n-1;
            sum+=(n-1)*(1+(n-2)*2);
            m-=n-1;
            if(m>0){
                sum-=min(m,n-1)*2;
                m-=n-1;
            }
            for(ll i=n-3;i>=1;i--){
                if(m<=0) break;
                sum-=min(m,i)*2;
                m-=i;
            }
            sum=max(sum,n*(n-1));
        }
        else {
            ll x=n-(m+1);
            sum+=m;
            sum+=m*(1+(m-1)*2);
            sum+=2*x*(m+1)*n;
            sum+=(n-m-1)*(n-m-2)*n;
        }
        printf("%lld
",sum);
    }
}