突然翻出了幾份之前寫的程式碼，拿出來回顧一下。

題意：求保持森林中每個村子都有道路相通,且維修所需要的最少money

#include <iostream>
#include <queue>
using namespace std;

const int INF = 0x5fffffff;  //權值上限  
const int MAXPT = 30;       //頂點數上限  
const int MAXEG = 1000;     //邊數上限 

class Prim     /*鄰接表 + 優先佇列 + Prime 最小生成樹*/
{  
private:  
    int n,e;  //n個點
    int dis[MAXPT],head[MAXPT];
    bool visit[MAXPT];
  
    struct Node  
    {
        int v,dis;
        Node () {}
        Node (int _v,int _dis)
        {
            v=_v;
            dis=_dis;
        }
        bool operator < (const Node a) const
        {
            return dis>a.dis;
        }
    };

    struct Edge
    {
        int v, w, next;
        Edge () {}
        Edge (int _v, int _next, int _w)
        {
            v=_v;
            next=_next;
            w=_w;
        }
    }edges[MAXEG];

public:
	inline void init (int vx)
    {
        n = vx;
        e = 0;
        memset(head,-1,sizeof(int) * (vx + 1));
		memset(visit,false,sizeof(visit));
    }
    
    inline void Add (int u, int v, int w)
    {
        edges[e] = Edge(v, head[u], w);
        head[u] = e++;
    }

	int prim (int src)
	{
		int cost=0,cnt=0;
		Node first;
		priority_queue<Node> Q;
		Q.push (Node(src, 0));
		while (!Q.empty() && cnt < n)
		{
			first=Q.top();
			Q.pop ();
			if (visit[first.v])
				continue;
			cost+=first.dis;
			cnt++;
			visit[first.v]=true;
			
			for (int i=head[first.v];i!=-1;i=edges[i].next)
				if (!visit[edges[i].v])
					Q.push (Node (edges[i].v,edges[i].w));
		}
		return cost;
	}
}ob;


int main ()
{
	int n;
	char str[5];
	while (~scanf("%d",&n),n)
	{
		ob.init (n);
		for (int i=1;i<n;i++)
		{
			int q,x,y,temp;
			scanf("%s%d",str,&q);
			x=str[0]-64;                               //將A變成1,將B變成2,以此類推
			while (q--)
			{
				scanf("%s%d",str,&temp);
				y=str[0]-64;
				ob.Add(x,y,temp);
				ob.Add(y,x,temp);
			}
		}
		printf("%d\n",ob.prim(1));
	}
	return 0;
}