AcWing 1146. 新的开始

题目思路
建立虚拟源点，求最小生成树
题目代码

#include <iostream>
#include <cstring>
#include <cstdio>

using namespace std;

const int N = 310, M = N * N;

int w[N][N];
int n;
int dist[N];
bool st[N];
int prim()
{
    memset(dist,0x3f,sizeof dist);

    dist[0] = 0;

    int res = 0;

    for(int i = 0;i <= n;i ++)
    {
        int t = -1;
        for(int j = 0;j <= n; j++)
        {
            if(!st[j] && (t == -1 || dist[j] < dist[t])) t = j;
        }

        st[t] = true;
        res += dist[t];

        for(int j = 0;j <= n; j++)
        {
            dist[j] = min(dist[j],  w[t][j]);
        }

    }

    return res;
}

int main()
{
    cin >> n;
    for(int i = 1;i <= n;i ++)
    {
        cin >> w[0][i];
        w[i][0] = w[0][i];
    }
    for(int i = 1;i <= n;i++)
    {
        for(int j = 1;j <= n;j++)
            cin >> w[i][j];
    }

    cout << prim() << endl;
    return 0;
}