hdu 4355 Party All the Time(三分)

 1 #include<bits/stdc++.h>
 2 #define F(i,a,b) for(int i=a;i<=b;i++)
 3 using namespace std;
 4 typedef pair<double,double>P;
 5 const int N=1e5+7;
 6 int t,n,cas;
 7 P a[N];
 8 
 9 double check(double mid)
10 {
11     double ans=0;
12     F(i,1,n)
13     {
14         double tmp=abs(a[i].first-mid);
15         ans+=tmp*tmp*tmp*a[i].second;
16     }
17     return ans;
18 }
19 
20 int main()
21 {
22     scanf("%d",&t);
23     while(t--)
24     {
25         scanf("%d",&n);
26         F(i,1,n)scanf("%lf%lf",&a[i].first,&a[i].second);
27         double l=0,r=1e6;
28         F(i,1,100)
29         {
30             double mid=(l+r)/2,mmid=(mid+r)/2;
31             if(check(mid)>check(mmid))l=mid;else r=mmid;
32         }
33         printf("Case #%d: %.0f\n",++cas,check(l));
34     }
35     return 0;
36 }