Problem:
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Connected Components

Write a program which reads relations in a SNS (Social Network Service), and judges that given pairs of users are reachable each other through the network.

Input

In the first line, two integer $n$ and $m$ are given. $n$ is the number of users in the SNS and $m$ is the number of relations in the SNS. The users in the SNS are identified by IDs $0, 1, ..., n-1$.

In the following $m$ lines, the relations are given. Each relation is given by two integers $s$ and $t$ that represents $s$ and $t$ are friends (and reachable each other).

In the next line, the number of queries $q$ is given. In the following $q$ lines, $q$ queries are given respectively. Each query consists of two integers $s$ and $t$ separated by a space character.

Output

For each query, print "yes" if $t$ is reachable from $s$ through the social network, "no" otherwise.

Constraints

$2 \leq n \leq 100,000$

$0 \leq m \leq 100,000$

$1 \leq q \leq 10,000$

Sample Input

10 9
0 1
0 2
3 4
5 7
5 6
6 7
6 8
7 8
8 9
3
0 1
5 9
1 3

Sample Output

yes
yes
no

Solution in C# (judge verdict: Accepted)

using System;
using System.Collections.Generic;
using System.Linq;

namespace ALDS1_11_D
{
    class Program
    {
        private static int n;
        private static int m;
        private static int q;
        private static Dictionary<int, List<int>> neighborDictionary;
        private static int[] graphGroup;
        static void Main(string[] args)
        {
            int[] tmpLine = Console.ReadLine()
                                   .Split(' ')
                                   .Select(s => int.Parse(s))
                                   .ToArray();
            Program.n = tmpLine[0];
            Program.m = tmpLine[1];

            Program.neighborDictionary = new Dictionary<int, List<int>>();
            Program.graphGroup = new int[Program.n];
            for (int i = 0; i < Program.n; i++)
            {
                Program.neighborDictionary.Add(i, new List<int>());
                Program.graphGroup[i] = -1;
            }
            
            for (int i = 0; i < Program.m; i++)
            {
                int[] tmpLine2 = Console.ReadLine()
                                       .Split(' ')
                                       .Select(s => int.Parse(s))
                                       .ToArray();
                Program.neighborDictionary[tmpLine2[0]].Add(tmpLine2[1]);
                Program.neighborDictionary[tmpLine2[1]].Add(tmpLine2[0]);
            }

            for (int i = 0; i < Program.n; i++)
            {
                if (Program.graphGroup[i] == -1)
                {
                    Program.DepthFirstSerach(i, i);
                }
            }
            
            Program.q = int.Parse(Console.ReadLine());

            for (int i = 0; i < Program.q; i++)
            {
                int[] tmpLine3 = Console.ReadLine()
                                        .Split()
                                        .Select(s => int.Parse(s))
                                        .ToArray();
                if (Program.graphGroup[tmpLine3[0]] == Program.graphGroup[tmpLine3[1]])
                {
                    Console.WriteLine("yes");
                }
                else
                {
                    Console.WriteLine("no");
                }
            }
        }

        private static void DepthFirstSerach(int groupID, int targetVertex)
        {
            Program.graphGroup[targetVertex] = groupID;

            Stack<int> stackToVisit = new Stack<int>();

            foreach (int neighbor in Program.neighborDictionary[targetVertex])
            {
                if (Program.graphGroup[neighbor] == -1)
                {
                    Program.DepthFirstSerach(groupID, neighbor);
                }
            }
        }
    }
}