洛谷P1546 最短网络 Agri-Net(Prim堆优化)

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