最小生成树 prim算法

#include<iostream>
#include<vector>
#include<algorithm>
using namespace std;
bool book[100];
const int inf = 2100000000;
int main()
{
    vector<int>u[100];
    vector<int>w[100];

    int n,m;
    cin>>n>>m;
    int x,y,s;
    for(int i=0;i<m;i++){
        cin>>x>>y>>s;
        u[y].push_back(x);
        u[x].push_back(y);
        w[x].push_back(s);
        w[y].push_back(s);
    }

    int dis[100];
    fill(dis,dis+99,inf);

    int num=0;
    dis[1]=0;
    int minn=inf;
    int t,ans=0;
    while(num!=n){
        minn=inf;
        for(int i=1;i<=n;i++){
            if(dis[i]<minn&&!book[i]){minn=dis[i];t=i;}
        }
        ans+=dis[t];num++;book[t]=true;
        for(int i=0;i<u[t].size();i++){
            if(w[t][i]<dis[u[t][i]]){
                dis[u[t][i]]=w[t][i];
            }
        }
    }
    cout<<ans<<endl;
}