1 #include<iostream> 2 #include<cstdio> 3 #include<cstring> 4 #include<algorithm> 5 #include<string> 6 #include<vector> 7 #include<set> 8 #include<map> 9 #include<queue> 10 #include<stack> 11 using namespace std; 12 const int inf=0xffffff; 13 const int MAXN=21; 14 int edges[MAXN][MAXN]; 15 int lowcost[MAXN]; 16 int nearvex[MAXN]; 17 int n,m; 18 void prim(int u0) 19 { 20 int i,j; 21 int sum=0; 22 for(i=1;i<=n;i++) 23 { 24 lowcost[i]=edges[u0][i]; 25 nearvex[i]=u0; 26 } 27 nearvex[u0]=-1; 28 for(i=1;i<n;i++) //找出n-1个顶点 29 { 30 int min=inf; 31 int v=-1; 32 for(j=1;j<=n;j++) 33 { 34 if(nearvex[j]!=-1&&lowcost[j]<min) 35 { 36 v=j; 37 min=lowcost[j]; 38 } 39 } 40 if(v!=-1) 41 { 42 printf("%d %d %d ",nearvex[v],v,lowcost[v]); 43 nearvex[v]=-1; 44 sum+=lowcost[v]; 45 for(j=1;j<=n;j++) 46 { 47 if(nearvex[j]!=-1&&edges[v][j]<lowcost[j]) 48 { 49 lowcost[j]=edges[v][j]; 50 nearvex[j]=v; 51 } 52 } 53 } 54 } 55 } 56 int main() 57 { 58 int i,j; 59 int u,v,w; 60 scanf("%d %d",&n,&m); 61 memset(edges,0,sizeof(edges)); 62 for(i=1;i<=m;i++) 63 { 64 scanf("%d%d%d",&u,&v,&w); 65 edges[u][v]=edges[v][u]=w; 66 } 67 for(i=1;i<=n;i++) 68 for(j=1;j<=n;j++) 69 { 70 if(i==j) 71 edges[i][j]=0; 72 else if(edges[i][j]==0) 73 edges[i][j]=inf; 74 } 75 prim(1); 76 return 0; 77 }