poj 2485 求最小生成树中 最长的一条边

Sample Input

1 //T

3 //n
0 990 692 //邻接矩阵
990 0 179
692 179 0
Sample Output

692

prim

 # include <iostream>
 # include <cstdio>
 # include <cstring>
 # include <algorithm>
 # include <cmath>
 # define LL long long
 using namespace std ;

 const int INF=0x3f3f3f3f;
 const int MAXN=;
 bool vis[MAXN];
 int lowc[MAXN];
 int n ;
 int cost[MAXN][MAXN] ;
 int MAX =  ;

 int Prim()//点是0~n-1
 {
     int ans=;
     memset(vis,false,sizeof(vis));
     vis[]=true;
     for(int i=;i<n;i++)lowc[i]=cost[][i];
     for(int i=;i<n;i++)
     {
         int minc=INF;
         int p=-;
         for(int j=;j<n;j++)
             if(!vis[j]&&minc>lowc[j])
             {
                 minc=lowc[j];
                 p=j;
             }
             if(minc==INF)return -;//原图不连通
             ans+=minc;
             if (minc > MAX)
                 MAX = minc ;
             vis[p]=true;
             for(int j=;j<n;j++)
                 if(!vis[j]&&lowc[j]>cost[p][j])
                     lowc[j]=cost[p][j];
     }
     return ans;
 }

 int main()
 {

    // freopen("in.txt","r",stdin) ;
     int T ;
     cin>>T ;
     while(T--)
     {
         cin>>n ;
         int w ;
         int i , j ;
         for (i =  ; i < n ; i++)
             for (j =  ; j < n ; j++)
                {
                    cin>>w ;
                    if(w==)
                      cost[i][j] = INF ;
                    else
                      cost[i][j] = w ;
                }
         MAX =  ;
         Prim() ;
         cout<<MAX<<endl ;

     }
     return  ;
 }