HDU 3932 groundhog build home -- Simulated Annealing

Question: http://acm.hdu.edu.cn/showproblem.php? PID = 1, 3932

Note that the distance from the farthest point is 0. Therefore, set the initial value to-1.

#include<iostream>#include<cstdio>#include<cstring>#include<algorithm>#include<ctime>#include<cmath>#include<cstdlib>#define db doubleusing namespace std;const int N=1005;const db dc=0.99,eps=1e-17,INF=2e4;int n,nx[N],ny[N],pid;db ans,px,py;int rdn(){  int ret=0;bool fx=1;char ch=getchar();  while(ch>‘9‘||ch<‘0‘){if(ch==‘-‘)fx=0;ch=getchar();}  while(ch>=‘0‘&&ch<=‘9‘) ret=(ret<<3)+(ret<<1)+ch-‘0‘,ch=getchar();  return fx?ret:-ret;}db dis(db x0,db y0,db x1,db y1){  return sqrt((x0-x1)*(x0-x1)+(y0-y1)*(y0-y1));}void SA(db T){  db x0=px,y0=py,pr=ans;int id=pid;  while(T>eps)    {      pr=-1;      for(int i=1;i<=n;i++)    {      db tmp=dis(x0,y0,nx[i],ny[i]);      if(tmp>pr)pr=tmp,id=i;    }      if(pr!=-1&&pr<ans)ans=pr,pid=id,px=x0,py=y0;      x0=x0+(nx[id]-x0)/pr*T; y0=y0+(ny[id]-y0)/pr*T;      T*=dc;    }}int main(){  srand(time(0));  int tx,ty;  while(scanf("%d%d%d",&tx,&ty,&n)==3)    {      for(int i=1;i<=n;i++)nx[i]=rdn(),ny[i]=rdn(),px+=nx[i],py+=ny[i];      px/=n; py/=n; ans=INF;      SA(10000);SA(10000);      printf("(%.1lf,%.1lf).\n%.1lf\n",px,py,ans);    }  return 0;}

 

HDU 3932 groundhog build home -- Simulated Annealing