Ural 1022 Genealogical tree

Ural 1022 Genealogical tree

My graph theory is poor.I had a better understanding of toposort through this problem.
Here is my code:

#include < iostream >
#include < string .h >
#define  maxn 107
using   namespace  std;
long  n,counter,path[maxn];
bool  used[maxn],g[maxn][maxn];
void  topo( long  s)
{
     for ( long  i = 1 ;i <= n;i ++ )
         if ( ! used[i] && g[s][i])
            topo(i);
    used[s] = true ;
    path[counter] = s;
    counter -- ;
}
int  main()
{
     /*
    freopen("data.in","r",stdin);
    freopen("data.out","w",stdout);
    // */
    cin >> n;
    memset(g, false , sizeof (g));
     for ( long  i = 1 ;i <= n;i ++ )
    {
         long  t;
         while (cin >> t && t)
            g[i][t] = true ;
    }
     //   Input
    counter = n;
    memset(used, false , sizeof (used));
     for ( long  i = 1 ;i <= n;i ++ )
         if ( ! used[i])
            topo(i);
     //   Topo Sort
     for ( long  i = 1 ;i <= n;i ++ )
    {
         if (i >= 2 ) cout << "   " ;
        cout << path[i];
    }
    cout << endl;
     //   Output
return   0 ;
}