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先坑著，聯賽活著回來的話我就寫（意思就是我絕對不會寫了）

 1 //minamoto
 2 #include<cstdio>
 3 #include<cmath>
 4 #include<ctime>
 5 #include<cstdlib>
 6 #define RD T*(rand()*2-RAND_MAX)
 7 #define double long double
 8 const int N=1005;
 9 double x[N],y[N],w[N];
10 const double D=0.97,EPS=1e-14
 
;
11 int n;
12 inline double calc(double x0,double y0){
13     double res=0,dx,dy;
14     for(int i=1;i<=n;++i){
15         dx=x[i]-x0,dy=y[i]-y0;
16         res+=sqrt(dx*dx+dy*dy)*w[i];
17     }
18     return res;
19 }
20 int main(){
21     double bx=0,by=0,best,ans,T,x0,y0,x1,y1,res;
22 //    freopen("testdata.in","r",stdin);
 

23     int times=1;
24     scanf("%d",&n);
25     for(int i=1;i<=n;++i){
26         scanf("%Lf%Lf%Lf",&x[i],&y[i],&w[i]);
27         bx+=x[i],by+=y[i];
28     }
29     best=ans=calc(bx/=n,by/=n);
30     srand(time(0));
31     while(times--){
32         ans=best,x0=bx,y0=by;
 
33         for(T=100000;T>EPS;T*=D){
34             x1=x0+RD;y1=y0+RD;
35             res=calc(x1,y1);
36             if(best>res) best=res,bx=x1,by=y1;
37             if(ans>res||exp((ans-res)/T)>(double)rand()/RAND_MAX)
38             ans=res,x0=x1,y0=y1;
39         }
40     }
41     printf("%.3Lf %.3Lf\n",bx,by);
42     return 0;
43 }

洛谷P1337 [JSOI2004]平衡點 / 吊打XXX（模擬退火）