prim算法求解最小生成树 C++实现

#include
#include
using namespace std;
const int N=510,INF=0x3f3f3f3f;
int g[N][N];
bool st[N];
int dist[N];
int n,m;
 
int prim(){
    memset(dist,0x3f,sizeof dist);
    int res=0;
    for(int i=0;i
        int t=-1;
        for(int j=1;j<=n;j++){
            if(!st[j] && (t==-1 || dist[t]>dist[j]))
                t=j;
        }
        if(i && dist[t]==INF) return INF;
        if(i) res += dist[t];
        for(int j=1;j<=n;j++) dist[j]=min(dist[j],g[t][j]);
        st[t]=true;
        
    }
    return res;
}
 
 
int main(){
    scanf("%d%d",&n,&m);
    memset(g,0x3f,sizeof g);
    
    while(m--){
        int a,b,c;
        scanf("%d%d%d",&a,&b,&c);
        g[a][b]=g[b][a]=min(g[a][b],c);
    }
    
    int t=prim();
    if(t==INF) puts("impossible");
    else printf("%d",t);
}