【POJ2420】A star not a tree?
阿新 • • 發佈:2017-06-14
string truct div clas urn return 模擬 cti get
蒟蒻開始學模擬退火……
起初一直不肯學,因為畢竟玄學算法……
哎呀玄學怎麽就沒用呢?對不對?
#include<iostream> #include<cstdio> #include<algorithm> #include<cstring> #include<cstdlib> #include<cmath> #include<ctime> using namespace std; int n; double xx,yy,ans,T; struct Point{double x,y;}p[110]; inlinedouble sqr(double x){return x*x;} inline double dis(double x,double y,Point p){ return sqrt(sqr(x-p.x)+sqr(y-p.y)); } inline double getsum(double x,double y){ double ret=0; for(int i=1;i<=n;i++)ret+=dis(x,y,p[i]); return ret; } int main(){ srand(time(NULL)); while(~scanf("%d",&n)){ xx=yy=0;ans=1e20;T=100000; for(int i=1;i<=n;i++){ scanf("%lf%lf",&p[i].x,&p[i].y); xx+=p[i].x;yy+=p[i].y; } xx/=n;yy/=n;ans=getsum(xx,yy); double tmp,x,y; while(T>=0.02){ x=y=0; for(int i=1;i<=n;i++){ x+=(p[i].x-xx)/dis(xx,yy,p[i]); y+=(p[i].y-yy)/dis(xx,yy,p[i]); } tmp=getsum(xx+x*T,yy+y*T); if(tmp<ans){ans=tmp;xx+=x*T;yy+=y*T;} else if(log((tmp-ans)/T)<(rand()%10000)/10000.0) {ans=tmp;xx+=x*T;yy+=y*T;} T*=0.9; } printf("%.0lf\n",ans); } }
【POJ2420】A star not a tree?