luogu 1337

这东西真玄学啊。。

在eps，delta，T之间改来改去。。。

在wa4，wa6，wa8之间轮转。

然后就过了。

爬山考虑合力然后移动即可。

eps要设的很小才行，布吉岛为森么

 1 #include <bits/stdc++.h>
 2 using namespace std;
 3 typedef double db;
 4 const db eps = 1e-14;
 5 const db delta = 0.993;
 6 const db INF = 1e100;
 7 struct point{
 8     db x,y,w;
 9     point operator + (const point &k1) const{return (point){k1.x+x,k1.y+y};}
10     point operator - (const point &k1) const{return (point){x-k1.x,y-k1.y};}
11     point operator * (db k1) const{return (point){x*k1,y*k1};}
12     db abs(){return sqrt(x*x+y*y);}
13     db dis(point k1){return ((*this)-k1).abs();}
14 };
15 point p[1005];int n;
16 db mxx=1e18;point ans;
17 void sa(){
18     db T = 2005;
19     while (T>eps){
20         db x=ans.x+(rand()*2-RAND_MAX)*T,y=ans.y+(rand()*2-RAND_MAX)*T;
21         db z=0;
22         for(int i=1;i<=n;i++)
23             z+=sqrt((p[i].x-x)*(p[i].x-x)+(p[i].y-y)*(p[i].y-y))*p[i].w;
24         if(z<mxx){
25             mxx=z;
26             ans={x,y};
27         }
28         T*=delta;
29     }
30 }
31 int main(){
32     scanf("%d",&n);
33     for(int i=1;i<=n;i++)scanf("%lf%lf%lf",&p[i].x,&p[i].y,&p[i].w);
34     sa();sa();sa();
35     printf("%.3f %.3f\n",ans.x,ans.y);
36 }

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