BZOJ 1379 模拟退火

模拟退火的第一题~

//By SiriusRen
#include <cmath>
#include <cstdio>
#include <algorithm>
using namespace std;
int cases,X,Y,M;
struct Point{double x,y,dis;}point[1005],b[33],ans,t;
double dis(Point a){
    double tmp=1e8;
    for(int i=1;i<=M;i++){
        double tx=a.x-point[i].x,ty=a.y-point[i].y;
        tmp=min(tmp,sqrt(tx*tx+ty*ty));
    }return tmp;
}
int main(){
    srand(1005730820),scanf("%d",&cases);
    while(cases--){
        scanf("%d%d%d",&X,&Y,&M),ans.dis=0;
        for(int i=1;i<=M;i++)scanf("%lf%lf",&point[i].x,&point[i].y);
        for(int i=1;i<=30;i++)b[i].x=rand()%X+1,b[i].y=rand()%Y+1,b[i].dis=dis(b[i]);
        for(double i=max(X,Y);i>=1e-3;i*=0.9)
            for(int j=1;j<=30;j++)
                for(int k=1;k<=30;k++){
                    double ran=rand();
                    t.x=b[j].x+cos(ran)*i,t.y=b[j].y+sin(ran)*i,t.dis=dis(t);
                    if(t.x<0||t.x>X||t.y<0||t.y>Y)continue;
                    if(t.dis>b[j].dis)b[j]=t;
                }
        for(int i=1;i<=30;i++)if(ans.dis<b[i].dis)ans=b[i];
        printf("The safest point is (%.1f, %.1f).\n",ans.x,ans.y);
    }
}