poj 1379 模拟退火算法的应用

学习自http://blog.csdn.net/dooder_daodao/article/details/6336879

 

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 1 #include<stdio.h>
 2 #include<math.h>
 3 #include<stdlib.h>
 4 #include<time.h>
 5 const double inf = 1e10;
 6 const double pi = acos(-1.0);
 7 const int Rp = 4;
 8 const int shift = 60;  
 9 struct point {
10     double x,y;
11     void goto_rand_dir(double key)
12     {
13         double d=2*pi*(double)rand()/RAND_MAX;
14         x+=key*sin(d);
15         y+=key*cos(d);
16     }
17     void Get_Rand_Point(int a,int b)
18     {
19         x=rand()%a+1;
20         y=rand()%b+1;
21     }
22 }p[1010],randp[Rp];
23 double Dis(point a,point b)
24 {
25     return (a.x-b.x)*(a.x-b.x)+(a.y-b.y)*(a.y-b.y);
26 }
27 double dis[Rp];
28 int main()
29 {
30     int t,i,j,k,x,y,m;
31     scanf("%d",&t);
32     srand(time(NULL));
33     while(t--)
34     {
35         scanf("%d%d%d",&x,&y,&m);
36         for(i=0;i<m;i++)
37         {
38             scanf("%lf%lf",&p[i].x,&p[i].y);
39         }
40         double tmp;
41         for(i=0;i<Rp;i++)
42         {
43             dis[i]=inf;
44             randp[i].Get_Rand_Point(x,y);
45             for(j=0;j<m;j++)
46             {
47                 tmp=Dis(randp[i],p[j]);
48                     if(tmp<dis[i])
49                         dis[i]=tmp;
50             }
51         }
52         double key=sqrt(1.0*(x*x+y*y))/2;
53         while(key>=0.01)
54         {
55             for(i=0;i<Rp;i++)
56             {
57                 for(j=0;j<shift;j++)
58                 {
59                     point cc=randp[i];
60                     cc.goto_rand_dir(key);
61                     if(cc.x<0||cc.y<0||cc.x>x||cc.y>y) continue;
62                     tmp=inf;
63                     for(k=0;k<m;k++)
64                     {
65                         double di=Dis(cc,p[k]);
66                         if(di<tmp)
67                             tmp=di;
68                     }
69                     if(tmp>dis[i]) 
70                     {
71                         dis[i]=tmp;
72                         randp[i]=cc;
73                     }
74                 }
75             }
76             key=key*0.8;
77         }
78         for(i=k=0;i<Rp;i++)
79             if(dis[i]>dis[k])
80                 k=i;
81             printf("The safest point is (%.1lf, %.1lf).\n",randp[k].x,randp[k].y);
82     }
83     return 0;
84 }