poj2031(Building a Space Station)

  1 #include <algorithm>
  2 #include <iostream>
  3 #include <sstream>
  4 #include <cstdlib>
  5 #include <cstring>
  6 #include <cstdio>
  7 #include <string>
  8 #include <bitset>
  9 #include <vector>
 10 #include <queue>
 11 #include <stack>
 12 #include <cmath>
 13 #include <list>
 14 //#include <map>
 15 #include <set>
 16 using namespace std;
 17 /***************************************/
 18 #define ll long long
 19 #define int64 __int64
 20 /***************************************/
 21 const int INF = 0x7f7f7f7f;
 22 const double eps = 1e-8;
 23 const double PIE=acos(-1.0);
 24 const int d1x[]= {0,-1,0,1};
 25 const int d1y[]= {-1,0,1,0};
 26 const int d2x[]= {0,-1,0,1};
 27 const int d2y[]= {1,0,-1,0};
 28 const int fx[]= {-1,-1,-1,0,0,1,1,1};
 29 const int fy[]= {-1,0,1,-1,1,-1,0,1};
 30 /*vector <int>map[N];map[a].push_back(b);int len=map[v].size();*/
 31 /***************************************/
 32 void openfile()
 33 {
 34     freopen("data.in","rb",stdin);
 35     freopen("data.out","wb",stdout);
 36 }
 37 priority_queue<int> qi1;
 38 priority_queue<int, vector<int>, greater<int> >qi2;
 39 /**********************华丽丽的分割线,以上为模板部分*****************/
 40 double map[200][200];
 41 int vis[200];
 42 double dis[200];
 43 int n;
 44 struct N
 45 {
 46     double x,y,z,r;
 47 } node[200];
 48 int EPS(double f) //处理精度问题
 49 {
 50     if (fabs(f)<eps) //e为科学计数法
 51         return 0;
 52     return f>0?1:-1;
 53 }
 54 double cha(int i,int j)
 55 {
 56     return sqrt((node[i].x-node[j].x)*(node[i].x-node[j].x)+(node[i].y-node[j].y)*(node[i].y-node[j].y)+(node[i].z-node[j].z)*(node[i].z-node[j].z))-node[i].r-node[j].r;
 57 }
 58 double dijstra()
 59 {
 60     int i,j,k;
 61     for(i=1; i<=n; i++)
 62     {
 63         dis[i]=map[1][i];
 64         vis[i]=0;
 65     }
 66     vis[1]=1;
 67     double sum=0;
 68     for(i=2; i<=n; i++)
 69     {
 70         double min=INF;
 71         for(j=1; j<=n; j++)
 72             if (min>dis[j]&&!vis[j])
 73             {
 74                 min=dis[j];
 75                 k=j;
 76             }
 77         vis[k]=1;
 78         sum+=min;
 79         for(j=1; j<=n; j++)
 80             if (map[k][j]<dis[j]&&!vis[j])
 81                 dis[j]=map[k][j];
 82     }
 83     return sum;
 84 }
 85 int main()
 86 {
 87 
 88     while(scanf("%d",&n)&&n)
 89     {
 90         int i,j;
 91         for(i=0; i<=n; i++)
 92             for(j=0; j<=n; j++)
 93                 map[i][j]=INF;
 94         for(i=1; i<=n; i++)
 95             scanf("%lf%lf%lf%lf",&node[i].x,&node[i].y,&node[i].z,&node[i].r);
 96         for(i=1; i<=n; i++)
 97             for(j=1; j<=n; j++)
 98             {
 99                 if (i==j)
100                     continue;
101                 double ce=cha(i,j);
102                 int ce1=EPS(ce);
103                 if (ce>map[i][j])
104                     continue;
105                 if (ce1>0)
106                 {
107                     map[i][j]=ce;
108                     map[j][i]=ce;
109                 }
110                 else
111                 {
112                     map[i][j]=0;
113                     map[j][i]=0;
114                 }
115             }
116         double cnt=dijstra();
117         printf("%.3lf\n",cnt);
118     }
119     return 0;
120 }