洛谷P1337 [JSOI2004]平衡点 / 吊打XXX（模拟退火）

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先坑着，联赛活着回来的话我就写（意思就是我绝对不会写了）

 //minamoto
 #include<cstdio>
 #include<cmath>
 #include<ctime>
 #include<cstdlib>
 #define RD T*(rand()*2-RAND_MAX)
 #define double long double
 const int N=;
 double x[N],y[N],w[N];
 const double D=0.97,EPS=1e-;
 int n;
 inline double calc(double x0,double y0){
     double res=,dx,dy;
     for(int i=;i<=n;++i){
         dx=x[i]-x0,dy=y[i]-y0;
         res+=sqrt(dx*dx+dy*dy)*w[i];
     }
     return res;
 }
 int main(){
     double bx=,by=,best,ans,T,x0,y0,x1,y1,res;
 //    freopen("testdata.in","r",stdin);
     int times=;
     scanf("%d",&n);
     for(int i=;i<=n;++i){
         scanf("%Lf%Lf%Lf",&x[i],&y[i],&w[i]);
         bx+=x[i],by+=y[i];
     }
     best=ans=calc(bx/=n,by/=n);
     srand(time());
     while(times--){
         ans=best,x0=bx,y0=by;
         for(T=;T>EPS;T*=D){
             x1=x0+RD;y1=y0+RD;
             res=calc(x1,y1);
             if(best>res) best=res,bx=x1,by=y1;
             if(ans>res||exp((ans-res)/T)>(double)rand()/RAND_MAX)
             ans=res,x0=x1,y0=y1;
         }
     }
     printf("%.3Lf %.3Lf\n",bx,by);
     return ;
 }