POJ 2420 A Star not a Tree?(模拟退火)

题目链接

居然1Y了，以前写的模拟退火很靠谱啊。

 1 #include <cstdio>

 2 #include <cstring>

 3 #include <string>

 4 #include <cmath>

 5 #include <ctime>

 6 #include <cstdlib>

 7 #include <iostream>

 8 using namespace std;

 9 struct point

10 {

11     double x,y;

12 }p[201];

13 int n;

14 int a[4] = {0,0,-1,1};

15 int b[4] = {1,-1,0,0};

16 double dis(double x1,double y1,double x2,double y2)

17 {

18     return sqrt((x1-x2)*(x1-x2)+(y2-y1)*(y2-y1));

19 }

20 double fun(double x,double y)

21 {

22     double ans = 0;

23     int i;

24     for(i = 0;i < n;i ++)

25     {

26         ans += dis(p[i].x,p[i].y,x,y);

27     }

28     return ans;

29 }

30 int main()

31 {

32     int T,i,key,num,j,k;

33     double tx,ty,ans,d,x,y;

34     srand(time(NULL));

35     scanf("%d",&n);

36     for(i = 0;i < n;i ++)

37     {

38         scanf("%lf%lf",&p[i].x,&p[i].y);

39     }

40     key = 5;

41     ans = 100000000;

42     num = 200;

43     x = p[0].x;

44     y = p[0].y;

45     T = 40;

46     while(T--)

47     {

48         for(i = 1;i <= num;i ++)

49         {

50             for(j = 0;j < 4;j ++)

51             {

52                 k = rand()%key;

53                 tx = x + k*a[j]*T;

54                 ty = y + k*b[j]*T;

55                 if(tx >= 0&&tx <= 10000&&ty >= 0&&ty <= 10000)

56                 {

57                     d = fun(tx,ty);

58                     if(ans > d)

59                     {

60                         ans = d;

61                         x = tx;

62                         y = ty;

63                     }

64                 }

65             }

66         }

67     }

68     printf("%.f\n",ans);

69     return 0;

70 }