题目描述

blablabla

样例

blablabla

算法1

(暴力枚举) $O(n^2)$

blablabla

时间复杂度

参考文献

C++ 代码

#include<iostream>
#include<cstring>
#include<algorithm>
using namespace std;
const int N = 510, INF = 0x3f3f3f3f;
int n,m;
int dist[N];
int g[N][N];
bool st[N];

int prim()
{
    memset(dist,INF,sizeof dist);
    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[t] > dist[j]))
            t = j;

        if(i&&dist[t]==INF) return INF;
        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()
{
    cin >> n >> m;
    memset(g,INF,sizeof g);
    for(int i =0 ; i < m; i ++ )
    {
        int a,b,c;
        cin >> a >> b >> c;
        g[a][b] = g[b][a] = min(g[a][b],c);
    }
    int t = prim();
    if(t==INF) cout << "impossible" << endl;
    else cout << t << endl;
    return 0;
}