I have WA1:(. Here is my program:
#include <iostream>
using namespace std;
#define N 100
int a[101][101];
bool Nnew[101];
int vc[N];
int next=0;
bool DFS_rec(int v, int next,int n)
{

     vc[v]=(next+1)%2;
     Nnew[v]=false;
     for(int j = 1; j <= n; j++)
     if(a[v][j]&&Nnew[j])
     {
        if(vc[j] == -1)
        {if(!DFS_rec(j, vc[v], n))return false;}
        else if(vc[j] != next)return false;
        return true;
     }
}
int main()
{
short n;
cin>>n;
int j=1;
for(int i=1;i<=n;i++)
    {
    while(j!=0)
        {
            cin>>j;
            a[i][j]=1;
            a[j][i]=1;
        }
      j=1;
    }

for(int j=1;j<=N;j++)
{
    Nnew[j]=true;
    vc[j]=-1;
}
DFS_rec(1,1,n);
for(int i=1;i<=n;i++)
if(vc[i]==-1)
{
    cout<<vc[i];
    goto end;
}
if(DFS_rec(1,1,n))
{
    for(int i=1;i<=n;i++)
        cout<<vc[i];
}
cout<<endl;
end: return 0;
}

Edited by author 07.01.2007 15:17