hdu4310 贪心

考虑每次血口的要少 就按照一滴血多少伤害来计算。由于直接相除有小数。考虑x/y > a/b  =>  x*b >y*a;

#include<stdio.h>
#include<string.h>
#include<algorithm>
using namespace std;

struct node
{
    int hp;
    int dps;
}a[25];
bool cmp(node a,node b)
{
    return a.dps*b.hp>a.hp*b.dps;
}
int main()
{
    int i,j,n;
    int sum;
    while(scanf("%d",&n)!=EOF)
    {
        sum=0;
        for(i=0;i<n;i++)
        {
            scanf("%d%d",&a[i].dps,&a[i].hp);
            sum+=a[i].dps;
        }
        sort(a,a+n,cmp);
        int all=0;
        for(i=0;i<n;i++)
        {
            all+=sum*a[i].hp;
            sum-=a[i].dps;
        }
        printf("%d\n",all);
    }
}