BZOJ 3680 吊打XXX 模拟退火

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首先这题应该改名叫吊打出题人

题目大意：给定n个质点，求重心

这n个质点的重心满足Σ(重心到点i的距离)*g[i]最小

模拟退火的裸题

尼玛交了两篇死活过不去各种改参数最后发现是我的INF不够大尼玛！

这题INF开0x3f妥妥过不去。。。起码要max_of _long_long附近才可以

最后写了10188MS，BZOJ倒数第一……这也是种艺术啊0.0

#include<cmath>#include<cstdio>#include<cstring>#include<iostream>#include<algorithm>#define M 10100using namespace std;struct point{double x,y,g;}points[M],ans;int n;double minans=23333333333333333ll;double dis(const point &x,const point &y){return sqrt( (x.x-y.x)*(x.x-y.x) + (x.y-y.y)*(x.y-y.y) );}double Judge(const point &p){int i;double re=0;for(i=1;i<=n;i++)re+=points[i].g*dis(p,points[i]);if(re<minans)ans=p,minans=re;return re;}double Rand(){return rand()%1000/1000.0;}void SA(double T){int i;point Now=ans;while(T>0.001){point Neo;Neo.x=Now.x+T*(Rand()*2-1);Neo.y=Now.y+T*(Rand()*2-1);double dE = Judge(Now) - Judge(Neo) ;if( dE > 0 || exp(dE/T)>Rand() )Now=Neo;T*=0.993;}for(i=1;i<=1000;i++){point Neo;Neo.x=ans.x+T*(Rand()*2-1);Neo.y=ans.y+T*(Rand()*2-1);Judge(Neo);}}int main(){int i;srand(19970815);cin>>n;for(i=1;i<=n;i++){scanf("%lf%lf%lf",&points[i].x,&points[i].y,&points[i].g);ans.x+=points[i].x;ans.y+=points[i].y;}ans.x/=n;ans.y/=n;SA( 1000000 );printf("%.3lf %.3lf\n",ans.x,ans.y);}

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