Networking(prim)

#include <iostream>
#include <cstring>
using namespace std;
const int N = 110;
int g[N][N],dist[N];
bool st[N];
int n,m;
int prim(){
    memset(dist,0x3f,sizeof dist);
    memset(st,false,sizeof st);//输出结果全为0，检查了数据正常读入后，发现此处初始化数组写成了dist，导致全变0
    int res = 0;
    for(int i = 0;i < n;i++){
        int t = -1;
        for(int j = 1;j <= n;j++){
            if(!st[j] && (t == -1 || dist[j] < dist[t])) t = j;
        }
        if(i) res += dist[t];
        st[t] = true;
        for(int j = 1;j <= n;j++){
            dist[j] = min(dist[j],g[t][j]);
        }
    }
    return res;
}
int main(){
    while(cin >> n && n){
        memset(g,0x3f,sizeof g);
        cin >> m;
        for(int i = 1;i <= m;i++){
            int a,b,w;
            cin >> a >> b >> w;
            g[a][b] = g[b][a] = min(g[a][b],w);
            // cout << a << " " << b <<  ' ' << g[a][b] << endl;            
        }
        int t = prim();
        cout << t << endl;
    }
    return 0;
}