Uva 11538

http://uva.onlinejudge.org/index.php?option=com_onlinejudge&Itemid=8&page=show_problem&problem=2533

公式推导

代码：

#include <iostream>
#include <cstdio>
#include <string>
#include <cstring>
#include <cmath>
#include <algorithm>

#define ll long long
using namespace std;

int main()
{
    //freopen("data.in","r",stdin);
    ll n,m;
    while(cin>>n>>m)
    {
        if(!n&&!m)break;

        if(n>m)
        swap(n,m);
        long long sum=0;
        sum+=(n*m*(m-1));
        sum+=(m*n*(n-1));
        sum+=((n*(n-1)*(n-2)*2/3+(m-n+1)*n*(n-1)))*2;
        cout<<sum<<endl;
    }
    return 0;
}