最小生成树prime+邻接表+优先队列

#include <cstdio>
#include <cstring>
#include <cstdlib>
#include <cmath>
#include <vector>
#include <map>
#include <set>
#include <stack>
#include <queue>
#include <string>
#include <iostream>
#include <algorithm>
using namespace std;
const long MAXN=10000;
struct Edge
{
    long v;
    long next;
    long cost;
}e[MAXN];
struct node
{
    long v;
    long cost;
};
bool operator <(const node &a,const node &b)
{
    return a.cost>b.cost;
}
priority_queue<node> q;
long p[MAXN],m,n,from,to,cost;
bool vist[MAXN];
void init()
{
    memset(p,-1,sizeof(p));
    memset(vist,0,sizeof(vist));
    while (!q.empty()) q.pop();
    long i,eid=0;
    for (i=0; i<n; ++i)
    {
        scanf("%ld %ld %ld",&from,&to,&cost);
        e[eid].next=p[from];
        e[eid].v=to;
        e[eid].cost=cost;
        p[from]=eid++;
        //以下适用于无向图
//        swap(from,to);
//        e[eid].next=p[from];
//        e[eid].v=to;
//        e[eid].cost=cost;
//        p[from]=eid++;
    }
}
void Prime()
{
    long cost=0;
    init();
    node t;
    t.v=from;//选择起点
    t.cost=0;
    q.push(t);
    long tt=0;
    while (!q.empty()&&tt<m)
    {
        t=q.top();q.pop();
        if (vist[t.v]) continue;//由于加的时候可能加多、重，所以要跳过这个点
        cost+=t.cost;
        ++tt;
        vist[t.v]=true;
        long j;
        for (j=p[t.v]; j!=-1; j=e[j].next)//加下一堆边
        {
            if (!vist[e[j].v])
            {
                node temp;
                temp.v=e[j].v;
                temp.cost=e[j].cost;
                q.push(temp);
            }
        }
    }
    printf("%ld\n",cost);
}

int main()
{
    while (scanf("%ld%ld",&m,&n)!=EOF)
    {
        Prime();
    }
    return 0;
}