HDU 4310 Hero

题目地址：​​点击打开链接​​

思路：巧妙之处是用乘法表示了除法的比较关系，虽然用int类型也能过，但最好用__int64类型

AC代码：

#include <iostream>
#include<algorithm>

using namespace std;

struct ghost
{
    int hp;
    int dp;
}a[25];

bool cmp(ghost a,ghost b)
{
    if(a.dp * b.hp != b.dp * a.hp)
        return a.dp * b.hp > b.dp * a.hp;
    else
        return a.hp < b.hp;
}
int main()
{
    int n,i;
    __int64 sum,count;
    while(cin>>n)
    {
        count = 0;
        sum = 0;
        for(i=0; i<n; i++)
        {
            cin>>a[i].dp>>a[i].hp;
            count += a[i].dp;
        }
        sort(a,a+n,cmp);
        for(i=0; i<n; i++)
        {
            sum += count * a[i].hp;
            count -= a[i].dp;
        }
        cout<<sum<<endl;
    }
    return 0;
}