poj1379 模拟退火

 1 //Accepted    220 KB    829 ms
 2 #include <cstdio>
 3 #include <cstring>
 4 #include <cmath>
 5 #include <ctime>
 6 #include <cstdlib>
 7 #include <iostream>
 8 using namespace std;
 9 const int iL=30;
10 const int iP=30;
11 const double inf=10000000.0;
12 const double Pi=acos(-1.0);
13 int n;
14 int T;
15 double boundary_x,boundary_y;
16 int cnt;
17 double hole_x[1005],hole_y[1005];
18 double x[iP],y[iP],dis[iP];
19 double min(double a,double b)
20 {
21     if (a-b<1e-12)
22     return a;
23     return b;
24 }
25 double get_dis(double x1,double y1,double x2,double y2)
26 {
27     return sqrt((x1-x2)*(x1-x2)+(y1-y2)*(y1-y2));
28 }
29 void sa()
30 {
31     srand(time(NULL));
32     for (int i=0;i<iP;i++)
33     {
34         x[i]=double(rand()%1000+1)/1000.0*boundary_x;
35         y[i]=double(rand()%1000+1)/1000.0*boundary_y;
36         dis[i]=inf;
37         for (int j=0;j<cnt;j++)
38         {
39             if (dis[i]>get_dis(x[i],y[i],hole_x[j],hole_y[j]))
40             dis[i]=get_dis(x[i],y[i],hole_x[j],hole_y[j]);
41         }
42     }
43     double delta=sqrt(boundary_x*boundary_x+boundary_y*boundary_y);
44     while (delta>0.0001)
45     {
46         for (int i=0;i<iP;i++)
47         {
48             double temp_x=x[i],temp_y=y[i],temp_dis=dis[i];
49             for (int j=0;j<iL;j++)
50             {
51                 double theta=double(rand()%1000+1)/1000.0*2*Pi;
52                 double nx=x[i]+delta*cos(theta);
53                 double ny=y[i]+delta*sin(theta);
54                 if (nx<0 || nx>boundary_x || ny<0 || ny>boundary_y)
55                 continue;
56                 double ndis=inf;
57                 for (int k=0;k<cnt;k++)
58                 ndis=min(ndis,get_dis(nx,ny,hole_x[k],hole_y[k]));
59                 if (ndis>temp_dis)
60                 {
61                     temp_dis=ndis;
62                     temp_x=nx;
63                     temp_y=ny;
64                 }
65             }
66             x[i]=temp_x;
67             y[i]=temp_y;
68             dis[i]=temp_dis;
69         }
70         delta*=0.8;
71     }
72 }
73 int main()
74 {
75     scanf("%d",&T);
76     while (T--)
77     {
78         scanf("%lf%lf%d",&boundary_x,&boundary_y,&cnt);
79         for (int i=0;i<cnt;i++)
80         scanf("%lf%lf",&hole_x[i],&hole_y[i]);
81         sa();
82         int tid;
83         double temp_dis=0;
84         for (int i=0;i<iP;i++)
85         {
86             if (dis[i]>temp_dis)
87             {
88                 tid=i;
89                 temp_dis=dis[i];
90             }
91         }
92         printf("The safest point is (%.1lf, %.1lf).\n",x[tid],y[tid]);
93     }
94     return 0;
95 }