最小生成树模板题
注意最后输出用%f
（从C99开始%f已经不能用于输出double 即 输入用%lf 输出用%f）
1 #include<cstdio> 2 #include<algorithm> 3 #include<cmath> 4 #include<cstring> 5 #include<string> 6 #define M(a,b) memset(a,b,sizeof(a)) 7 #define debug(x) cerr<<#x<<"=="<<(x)<<endl 8 using namespace std; 9 typedef long long ll; 10 11 const int maxn=110; 12 13 int f[maxn],tol,n; 14 15 struct _edge 16 { 17 int u,v; 18 double w; 19 }edge[maxn*maxn*maxn]; 20 21 bool cmp(_edge a,_edge b) 22 { 23 return a.w<b.w; 24 } 25 26 struct point 27 { 28 int a; 29 double x,y,z,r; 30 } pt[maxn]; 31 32 void addedge(point a,point b) 33 { 34 edge[tol].u=a.a; 35 edge[tol].v=b.a; 36 double len=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))-a.r-b.r; 37 edge[tol].w=len<0?0:len; 38 tol++; 39 } 40 41 //void addedge(int u,int v,int w) 42 //{ 43 // edge[tol].u=u; 44 // edge[tol].v=v; 45 // edge[tol].w=w; 46 // tol++; 47 //} 48 49 int _find(int x) 50 { 51 if(f[x]==-1) return x; 52 else return f[x]=_find(f[x]); 53 } 54 55 double kruskal() 56 { 57 M(f,-1); 58 sort(edge,edge+tol,cmp); 59 int cnt=0; 60 double ans=0,w; 61 int u,v,f1,f2; 62 for(int i=0; i<tol; i++) 63 { 64 u=edge[i].u; 65 v=edge[i].v; 66 w=edge[i].w; 67 f1=_find(u); 68 f2=_find(v); 69 if(f1!=f2) 70 { 71 ans+=w; 72 f[f1]=f2; 73 cnt++; 74 } 75 if(cnt==n-1) break; 76 } 77 return ans; 78 } 79 80 int main() 81 { 82 while(scanf("%d",&n)!=EOF&&n) 83 { 84 tol=0; 85 double x,y,z,r; 86 for(int i=0; i<n; i++) 87 { 88 pt[i].a=i; 89 scanf("%lf%lf%lf%lf",&pt[i].x,&pt[i].y,&pt[i].z,&pt[i].r); 90 for(int j=0; j<i; j++) 91 { 92 addedge(pt[j],pt[i]); 93 } 94 } 95 96 printf("%.3f ",kruskal()); //注意要用%f 97 } 98 return 0; 99 } 100 /* 101 102 3 103 10.000 10.000 50.000 10.000 104 40.000 10.000 50.000 10.000 105 40.000 40.000 50.000 10.000 106 2 107 30.000 30.000 30.000 20.000 108 40.000 40.000 40.000 20.000 109 5 110 5.729 15.143 3.996 25.837 111 6.013 14.372 4.818 10.671 112 80.115 63.292 84.477 15.120 113 64.095 80.924 70.029 14.881 114 39.472 85.116 71.369 5.553 115 0 116 117 */