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;
using System.Text;
using System.Threading.Tasks;

namespace lec11D
{
    public class Element
    {
        public int id;
        public List<int> fri_list;
        public int group;

        public Element()
        {
            fri_list = new List<int>();
            group = -1;
        }

    }
    class Program
    { 
       static  Element[] arr;

        static void Main(string[] args)
        {

            //setting part

            string [] num_inp = Console.ReadLine().Split(' ');
            var n = int.Parse(num_inp[0]);
            var m = int.Parse(num_inp[1]);

             arr = new Element[n];

            for (int i = 0; i < n; i++)
            {
                arr[i] = new Element
                {
                    id = i
                };
            }

            //input part

            for (int i = 0; i < m; i++)
            {
                string[] fri_inp = (Console.ReadLine()).Split(' ');
                var s = int.Parse(fri_inp[0]);
                var t = int.Parse(fri_inp[1]);

                arr[s].fri_list.Add(t);
                arr[t].fri_list.Add(s);
            }

            Adjust();

            //quetion part

            int q = int.Parse(Console.ReadLine());

            for (int i = 0; i < q; i++)
            {
                string[] q_inp = (Console.ReadLine()).Split(' ');
                var s = int.Parse(q_inp[0]);
                var t = int.Parse(q_inp[1]);
                if (arr[s].group == arr[t].group)
                {
                    Console.WriteLine("yes");
                }
                else
                {
                    Console.WriteLine("no");
                }
            }

            Console.ReadLine();
        }

        static void Adjust()
        {
            var g = 1;
            foreach (var i in arr)
            {
                if (i.group == -1)
                {
                    DFS(i,g);
                    g++;
                }
            }
        }

        static void DFS(Element t,int g)
        {
            t.group = g;
            Stack<int> stk = new Stack<int>();
            stk.Push(t.id);
       
            while ( stk.Count != 0)
            {
                int tag = stk.Pop();
                foreach(int next in arr[tag].fri_list)
                {
                    if (arr[next].group == -1)
                    {
                        stk.Push(next);
                        arr[next].group = g;
                    }
                }
            }
        }
    }
}