Go: package main

import (
	"fmt"
	"os"
	"bufio"
	"strconv"
	"container/list"
	"bytes"
)

const MaxNode int = 1e5

var graph [][] int
var color []int
var N int

func bfs(u, c int) {
	l := list.New()
	l.PushBack(u)
	for ;l.Len()!=0; {
		u = l.Front().Value.(int)
		color[u] = c
		l.Remove(l.Front())
		for i:=0; i<len(graph[u]); i++ {
			if color[graph[u][i]] == 0 {
				l.PushBack(graph[u][i])
			}
		}
	}
}

func assignColor() {
	id := 1
	for u:=0; u<N; u++ {
		if color[u] == 0 {
			bfs(u, id)
			id ++
		}
	}
}

func nextInt(scanner *bufio.Scanner) int {
	scanner.Scan()
	num, _ := strconv.Atoi(scanner.Text())
	return num
}


func buildGraph(scanner *bufio.Scanner) {
	N = nextInt(scanner)
	color = make([]int, N)
	graph = make([][]int, N)
	m := nextInt(scanner)
	for i:=0; i<m; i++ {
		n1 := nextInt(scanner)
		n2 := nextInt(scanner)
		graph[n1] = append(graph[n1], n2)
		graph[n2] = append(graph[n2], n1)
	}
}

func answer(scanner *bufio.Scanner) {
	var outBuffer bytes.Buffer
	cnt := nextInt(scanner)
	for i:=0; i<cnt; i++ {
		n1 := nextInt(scanner)
		n2 := nextInt(scanner)
		if color[n1] == color[n2] {
			outBuffer.WriteString("yes\n")
		} else {
			outBuffer.WriteString("no\n")
		}
	}
	fmt.Printf("%s", outBuffer.String())
}

func main() {
	scanner := bufio.NewScanner(os.Stdin)
	scanner.Split(bufio.ScanWords)
	buildGraph(scanner)
	assignColor()
	answer(scanner)
}

C++: #include <bits/stdc++.h>
using namespace std;
#define rep(i, n) for (int i = 0; i < n; i++)

int MAX = 100000;

vector<vector<int>> user(MAX, vector<int>(0));
vector<int> group(MAX, -1);

// 模範回答
// void dfs(int start, int group_i) {
//     stack<int> s;
//     group[start] = group_i;
//     s.push(start);
//     while (!s.empty()) {
//         int current = s.top();
//         s.pop();
//         for (int i = 0; i < user[current].size(); i++) {
//             int adj = user[current][i];
//             if (group[adj] == NIL) {
//                 s.push(adj);
//                 group[adj] = group_i;
//             }
//         }
//     }
// }

// 再帰によるdfs
void dfs(int start, int group_i) {
    group[start] = group_i;
    rep(i, user[start].size()) {
        int adj = user[start][i];
        if (group[adj] == -1) {
            dfs(adj, group_i);
        }
    }
}

// スタックによるdfsパターン1
// void dfs(int start, int group_i) {
//     stack<int> s;
//     group[start] = group_i;
//     s.push(start);
//     while (!s.empty()) {
//         int current = s.top();
//         group[current] = group_i;
//         bool stop = true;
//         for (int i = 0; i < user[current].size(); i++) {
//             int adj = user[current][i];
//             if (group[adj] == -1) {
//                 s.push(adj);
//                 stop = false;
//                 break;
//             }
//         }
//         if (stop) s.pop();
//     }
// }

int main() {
    int n, m, s, t, q;
    scanf("%d %d", &n, &m);
    rep(i, m) {
        scanf("%d %d", &s, &t);
        user[s].push_back(t);
        user[t].push_back(s);
    }

    int group_i = 0;
    rep(i, n) {
        if (group[i] == -1) {
            dfs(i, group_i++);
        }
    }

    scanf("%d", &q);
    rep(i, q) {
        scanf("%d %d", &s, &t);
        if (group[s] == group[t]) printf("yes\n");
        else printf("no\n");
    }
}

C++: #include <iostream>
#include <stack>
#include <vector>

using namespace std;

void dfs(vector<vector<int>>& g, vector<int>& color, int id, int c) {
    stack<int> s;
    vector<bool> visited(g.size(), false);
    s.push(id);
    color[id] = c;
    while (!s.empty()) {
        int id = s.top();
        s.pop();
        visited[id] = true;

        for (int i = 0; i < g[id].size(); ++i) {
            int adj = g[id][i];
            if (!visited[adj]) {
                color[adj] = c;
                s.push(adj);
            }
        }
    }
}

void assign_colors(vector<vector<int>>& g, vector<int>& color) {
    int color_id = 1;
    for (int i = 0; i < g.size(); ++i) {
        if (color[i] == -1) {
            dfs(g, color, i, color_id);
            ++color_id;
        }
    }
}

int main() {
    ios::sync_with_stdio(false);

    int n, m;
    cin >> n >> m;

    vector<vector<int>> g(n);
    for (int i = 0; i < m; ++i) {
        int p1, p2;
        cin >> p1 >> p2;
        g[p1].push_back(p2);
        g[p2].push_back(p1);
    }

    vector<int> color(n, -1);
    assign_colors(g, color);

    int p;
    cin >> p;
    for (int i = 0; i < p; ++i) {
        int p1, p2;
        cin >> p1 >> p2;
        if (color[p1] == color[p2])
            cout << "yes\n";
        else
            cout << "no\n";
    }
}

C++: #include <iostream>
#include <queue>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <climits>
using namespace std;

int n;

vector<int> uf;

void initialize(int n)
{
  uf = vector<int>(n);
  for (int i = 0; i < n; i++)
    uf[i] = i;
}

int root(int i)
{
  if (uf[i] == i) return i;
  return uf[i] = root(uf[i]);
}

void unite(int i, int j)
{
  int ri = root(i);
  int rj = root(j);
  if (ri != rj)
    uf[rj] = ri;
}

bool same(int i, int j)
{
  return root(i) == root(j);
}

int main()
{
  int m, q;
  cin >> n >> m;

  initialize(n);
  for (int i = 0; i < m; i++) {
    int u, v; cin >> u >> v;
    unite(u, v);
  }

  cin >> q;
  for (int i = 0; i < q; i++) {
    int u, v; cin >> u >> v;
    cout << (same(u, v)?"yes":"no") << endl;
  }

  return EXIT_SUCCESS;
}

C++: #include <iostream>
#include <cstdio>
#include <algorithm>
#include <vector>
#include <utility>
#include <queue>
#include <stack>
#include <string>
#include <climits>
using namespace std;

#define MAX_N  100000
#define MAX_M  100000
#define MAX_Q  10000

int n, m, q, k, kind[MAX_N] = {};
queue<int> Q;

void bf(vector<vector<int> >& sns, int s)
{
    Q.push(s);
    while (!Q.empty()) {
        s = Q.front();
        Q.pop();
        kind[s] = k;
        for (int i = 0; i < sns[s].size(); i++) {
            if (!kind[sns[s][i]]) Q.push(sns[s][i]);
        }
    }
}

int main()
{
    cin >> n >> m;
    vector<vector<int> > sns(n);
    int s, d;
    while (m--) {
        cin >> s >> d;
        sns.at(s).push_back(d);
        sns.at(d).push_back(s);
    }
    k = 0;
    for (int s = 0; s < n; s++) {
        if (!kind[s]) {
            k++;
            bf(sns, s);
        }
    }
    cin >> q;
    while (q--) {
        cin >> s >> d;
        cout << (kind[s] == kind[d] ? "yes" : "no") << endl;
    }
    return 0;
}

C++: #include <bits/stdc++.h>
using namespace std;
typedef long long ll;
#define rep(i, start, n) for (int i = (int)(start); i < (int)(n); ++i)
void search(vector<vector<int> > &G, int *color, int s, int id)
{
    color[s] = id; //sは訪問済み
    stack<int> q;
    q.push(s);
    while (q.empty() == false)
    {
        int p = q.top();
        q.pop();
        rep(i, 0, G[p].size())
        {
            int new_p = G[p][i];
            if (color[new_p] == 0)
            {
                color[new_p] = id;
                q.push(new_p);
            }
        }
    }
}
int main()
{
    int n, m;
    cin >> n >> m;
    vector<vector<int> > G(n, vector<int>(0));
    int color[n] = {};
    int s, t;
    rep(i, 0, m)
    {
        scanf("%d %d", &s, &t);
        G[s].push_back(t);
        G[t].push_back(s);
    }
    int id(0);
    rep(i, 0, n)
    {
        if (color[i] == 0)
        {
            search(G, color, i, ++id);
        }
    }
    int q;
    cin >> q;
    rep(i, 0, q)
    {
        scanf("%d %d", &s, &t);
        if (color[s] == color[t])
            printf("yes\n");
        else
            printf("no\n");
    }
}