Poj Solution 2457

http://poj.org/problem?id=2457

//* @author: ccQ.SuperSupper
import java.io.*;
import java.util.*;
public class Main {
    static final int N = 10000+10;
    static int meat[] = new int[N],pre[] = new int[N],n,K;
    static Vector Graph[] = new Vector[N];
    static Queue que = new LinkedList<Integer>();
    static void start(){
        for(int i=0;i< N;++i)
            Graph[i] = new Vector();
    }
    static void init(){
        que.clear();
        for(int i=0;i< N;++i){
            Graph[i].clear();
            meat[i] = N+N;
            pre[i] = -1;
        }
        meat[1] = 1;
        que.offer(1);
    }

 public static void main(String[]args) throws Exception{
  int i,u,v;
  start();
  init();
  StreamTokenizer cin = new StreamTokenizer(new BufferedReader(new InputStreamReader(System.in)));

  n = Get_Num(cin);
  K = Get_Num(cin);
  for(i=0;i< n;++i){
    v = Get_Num(cin);
    u = Get_Num(cin);
    Graph[v].add(u);
  }

  solve();
  if(meat[K]>=N) System.out.println(-1);
  else{
    System.out.println(meat[K]);
    make_ans();
  }
 }
 
  static void solve(){
   int i,j,k,temp;
   while(!que.isEmpty()){
    temp = (Integer) que.element();
    que.remove();
    k = Graph[temp].size();
    for(i=0;i< k;++i){
        j = (Integer) Graph[temp].elementAt(i);
        if(meat[j]>meat[temp]+1){
            meat[j] = meat[temp]+1;
            pre[j] = temp;
            que.add(j);
        }
    }
   }
 }

  static void make_ans(){
   int ans[] = new int[N],i,k=K,top=0;
   while(true){
    ans[top++] = k;
    k = pre[k];
    if(k< 0) break;
   }
   PrintWriter out = new PrintWriter(new OutputStreamWriter(System.out));
   for(i=top-1;i>=0;--i)
    out.println(ans[i]);
   out.flush();
 }

  static int Get_Num(StreamTokenizer cin) throws Exception{
   cin.nextToken();
   return (int) cin.nval;
 }
}