poj 2485 highways record the maximum edge in the minimum spanning tree

#include <iostream>
#include <memory.h>
#define IN (1<<28)
using namespace std;
int kase, N;
int G[505][505];
int locost[505], visited[505];
int cost, ans;
void prime()
{
   for( int i = 1; i <= N; i++ )
        locost[i] = G[1][i];
   locost[1] = 0;
   visited[1] = 1;
   int cnt = 0;
   while( cnt != N - 1 )
   {
       int MinV = 0, Min = IN;
       for( int i = 1; i <= N; i++ )
        if( locost[i] && locost[i] < Min )
       {
           MinV = i;
           Min = locost[i];
       }
       if( !MinV )
        break;
       cost += Min;
       cnt++;
       years = max(years, Min);
       locost[MinV] = 0;
       for( int i = 1; i <= N; i++ )
       {
           if( locost[i] && locost[i] > G[MinV][i] )
            locost[i] = G[MinV][i];
       }
   }
}
intmain()
{
    cin >> kase;
    while( kase-- )
    {
        cin >> N;
        memset(G, 0, sizeof(G));
        memset(locost, 0, sizeof(locost));
        memset(visited, 0, sizeof(visited));
        for( int i = 1; i <= N; i++ )
            for( int j = 1; j <= N; j++ )
            cin >> G[i][j];
        cost = 0;
        years = 0;
        prime();
        cout << ans << endl;
    }
    return 0;
}