洛谷P1546 最短网络 Agri-Net(Prim堆优化)

#include<bits/stdc++.h>
using namespace std;
const int maxn=5005;
const int INF=0x3f3f3f3f;
inline void read(int &tmp)
{
    int x=1;char c=getchar();
    for(tmp=0;!isdigit(c);c=getchar()) if(c=='-') x=-1;
    for(;isdigit(c);tmp=tmp*10+c-48,c=getchar());
    tmp*=x;
}
int n,sum,tot,m,mp[maxn][maxn],w[maxn];
typedef pair<int,int> P;
priority_queue< P,vector<P>,greater<P> >q;
bool v[maxn];
void Prim()
{
    memset(w,0x3f,sizeof(w));
    w[1]=0;q.push(make_pair(0,1));
    while(!q.empty())
    {
        int Top=q.top().second;q.pop();
        if(v[Top]) continue;
        v[Top]=1;sum+=w[Top];++tot;
        for(int i=1;i<=n;i++)
            if(mp[Top][i]<w[i]&&mp[Top][i]>0&&v[i]==false) {w[i]=mp[Top][i];q.push(make_pair(w[i],i));}
    }
} 
int main()
{
    read(n);
    for(int i=1;i<=n;i++)
        for(int j=1;j<=n;j++)
                {read(mp[i][j]);if(i==j) mp[i][j]=INF;}
    Prim();
    printf("%d",sum);
    return 0;
}