hdu 1162 Eddy's picture

http://acm.hdu.edu.cn/showproblem.php?pid=1162

 1 #include <cstdio>

 2 #include <cstring>

 3 #include <iostream>

 4 #include <cmath>

 5 #include <algorithm>

 6 #define maxn 200

 7 using namespace std;

 8 const int inf=1<<30;

 9 

10 double g[maxn][maxn];

11 int n;

12 bool vis[maxn];

13 double dist[maxn];

14 double sum;

15 struct node

16 {

17     double x,y;

18 }p[maxn];

19 

20 double sqr(double x)

21 {

22     return x*x;

23 }

24 

25 double dis(int x1,int y1,int x2,int y2)

26 {

27     return sqrt(sqr(x1-x2)+sqr(y1-y2));

28 }

29 

30 void prim()

31 {

32     memset(vis,false,sizeof(vis));

33     for(int i=1; i<=n; i++) dist[i]=g[1][i];

34     dist[1]=0;

35     vis[1]=true;

36     for(int i=1; i<n; i++)

37     {

38         double m=(double)inf;

39         int x;

40         for(int j=1; j<=n; j++) if(!vis[j]&&dist[j]<m) m=dist[x=j];

41         sum+=m;

42         vis[x]=true;

43         for(int j=1; j<=n; j++) if(!vis[j]) dist[j]=min(dist[j],g[x][j]);

44     }

45 }

46 

47 

48 int main()

49 {

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

51     {

52         for(int i=1; i<=n; i++)

53         {

54             cin>>p[i].x>>p[i].y;

55         }

56         for(int i=1; i<=n; i++)

57         {

58             for(int j=1; j<=n; j++)

59             {

60                 double d=dis(p[i].x,p[i].y,p[j].x,p[j].y);

61                 g[i][j]=g[j][i]=d;

62             }

63         }

64         sum=0;

65         prim();

66         printf("%.2lf\n",sum);

67     }

68     return 0;

69 }

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