graph_contester_detours_6

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading;
using System.IO;

namespace ConsoleApplication
{
    public class Graph
    {
        private class Node
        {
            List<List<int>> array = new List<List<int>>();
            int countOfVertex;
            private bool[] nov;

            public void NovSet()
            {
                for (int i = 0; i < countOfVertex; i++)
                    nov[i] = true;
            }

            public Node(List<List<int>> tmp, int n)
            {
                array = tmp;
                countOfVertex = n;
                nov = new bool[countOfVertex];
            }

            public void SearchSink(StreamWriter fout)
            {
                bool[] stocks = new bool[countOfVertex];
                for (int i = 0; i < countOfVertex; i++)
                    stocks[i] = true;
                for (int i = 0; i < countOfVertex; i++)
                {
                    NovSet();
                    Dfs(i);
                    for (int j = 0; j < countOfVertex; j++)
                        if (nov[j] == true) stocks[j] = false;
                }
                for(int i = 0; i < countOfVertex; i++)
                    if(stocks[i] == true) fout.Write("{0} ", i + 1);
            }

            public void Dfs(int vertex)
            {
                if ((!nov[vertex])) return;

                nov[vertex] = false;

                for(int j = 0; j < array.Count; j++)
                    if (array[j][0] == vertex)
                    {
                        for (int i = 0; i < 2; i++)
                            Dfs(array[j][i]);
                    }
            }
        }
        private Node graph;

        public Graph(string nameOfFile)
        {
            StreamReader fin = new StreamReader(nameOfFile);
            string[] nm = fin.ReadLine().Split(' ');
            int m = int.Parse(nm[0]);
            int n = int.Parse(nm[1]);
            List<List<int>> tmp = new List<List<int>>();
            for (int i = 0; i < n; i++)
            {
                List<int> tmp2 = new List<int>();
                string[] arr = fin.ReadLine().Split(' ');
                for (int j = 0; j < arr.Length; j++)
                    tmp2.Add(int.Parse(arr[j]) - 1);
                tmp.Add(tmp2);
            }
            fin.Close();
            graph = new Node(tmp, m);
        }

        public void SearchSink(string nameOfFile)
        {
            StreamWriter fout = new StreamWriter(nameOfFile);
            graph.SearchSink(fout);
            fout.Close();
        }
    }
    class Program
    {
        static void Main(string[] args)
        {
            Graph graph1 = new Graph("input.txt");
            graph1.SearchSink("output.txt");
        }
    }
}