HDU 4355 - Party All the Time

 

题目地址： http://acm.hdu.edu.cn/showproblem.php?pid=4355

 

三分~~ 

 

比赛时没看到 题目输出那里写的 四舍五入·~~   WA了几次~~  当时是GSS写的~~~。

 

这里我自己重新做了一下~~~

 

#include<iostream>#include<cstdio>#define mul(x,y) ((x)*(x)*(x)*(y))#define abs(x) ((x)<0?0-(x):(x))using namespace std;const int maxn=50010;const double eps = 1e-6;double x[maxn],w[maxn];int n;double res(double s){double sum=0,p;for(int i=0;i<n;i++){p=abs(x[i]-s);sum+=mul(p,w[i]);}return sum;} int main(){int t,tt;double sum;scanf("%d",&t);for(tt=1;tt<=t;tt++){scanf("%d",&n);for(int i=0;i<n;i++)scanf("%lf%lf",&x[i],&w[i]);double sum1,sum2,mid1,mid2,l=x[0],r=x[n-1];while(l<=r){mid1=(l+r)/2;mid2=(l+mid1)/2;sum1=res(mid1);sum2=res(mid2);if(mid2-eps<mid1 && mid1<mid2+eps) break;if(sum1>sum2) r=mid1; else l=mid2;}printf("Case #%d: %.0lf\n",tt,min(sum1,sum2));}return 0;}