POJ2069 最小球体覆盖, 模拟退火

只是套了个模板，模拟退火具体的过程真心不懂阿

 1 //#pragma comment(linker, "/STACK:16777216") //for c++ Compiler

 2 #include <stdio.h>

 3 #include <iostream>

 4 #include <cstring>

 5 #include <cmath>

 6 #include <stack>

 7 #include <queue>

 8 #include <vector>

 9 #include <algorithm>

10 #define ll long long

11 #define Max(a,b) (((a) > (b)) ? (a) : (b))

12 #define Min(a,b) (((a) < (b)) ? (a) : (b))

13 #define Abs(x) (((x) > 0) ? (x) : (-(x)))

14 using namespace std;

15 

16 const int INF = 0x3f3f3f3f;

17 const int MAXN = 220;

18 const double eps = 1e-8;

19 int n;

20 struct POINT{

21     double x,y,z;

22 }ps[35],q;

23 

24 double dist(POINT a,POINT b){

25     return sqrt((a.x-b.x)*(a.x-b.x)+(a.y-b.y)*(a.y-b.y)+(a.z-b.z)*(a.z-b.z));

26 }

27 

28 int maxD(POINT p){

29     double res = 0;

30     int i, k = 0;

31     for(i = 0; i < n ; ++i){

32         double tmp = dist(p,ps[i]);

33         if(tmp > res){

34             k = i;

35             res = dist(p,ps[i]);

36         }

37     }

38     return k;

39 }

40 

41 double BallCover(){

42     double step = 100, ans = INF;

43     q.x = q.y = q.z = 0.0;

44     while(step > eps){

45         int d = maxD(q);

46         double tmp = dist(ps[d],q);

47         if(tmp < ans) ans=tmp;

48         double dx = ps[d].x - q.x;

49         double dy = ps[d].y - q.y;

50         double dz = ps[d].z - q.z;

51         dx /= tmp;

52         dy /= tmp;

53         dz /= tmp;

54         q.x += (dx*step);

55         q.y += (dy*step);

56         q.z += (dz*step);

57         step *= 0.98;

58     }

59     return ans;

60 }

61 

62 int main(){

63     int i;

64     while(EOF != scanf("%d",&n)){

65         if(0 == n)  break;

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

67             scanf("%lf%lf%lf",&ps[i].x,&ps[i].y,&ps[i].z);

68         printf("%.5f\n",BallCover());

69     }

70     return 0;

71 }