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 <iostream>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <vector>
#include <queue>
using namespace std;
const int INF=1<<21;
const int maxn=100+10;
int n,m,q;
int p[maxn];
int rank[maxn];
void init(int n)
{
   for(int i=0;i<n;i++)
   {
       p[i]=i;
       rank[i]=0;
   }
}
int fnd(int x)
{
    int y=x;
    if(x==p[x]) return x;
    while(x!=p[x])
    {
        x=p[x];
    }
    return p[y]=x;
}
bool is_same(int x,int y)
{
   return fnd(x)==fnd(y);
}

void uni(int x,int y)
{
   x=fnd(x);
   y=fnd(y);
   if(rank[x]>rank[y])
   {
       p[y]=x;
       rank[y]++;
   }
   else
   {
       p[x]=y;
       rank[x]++;
   }
}

int main()
{
//    freopen("in.txt","r",stdin);
    scanf("%d%d",&n,&m);
    int x,y;
    init(n);
    for(int i=0;i<m;i++)
    {
        scanf("%d%d",&x,&y);
        uni(x,y);
    }
    scanf("%d",&q);
    while(q--)
    {
        scanf("%d%d",&x,&y);
        if(is_same(x,y)) printf("yes\n");
        else printf("no\n");
    }


    return 0;
}

C++: #include<iostream>
#include<vector>
#include<stack>
using namespace std;
int i, j, v, num, color[100000];
vector<int> list[100000];

void dfs(int r, int c){
 stack<int> S;
 S.push(r);
 color[r] = c;
 while( !S.empty() ){
   int u = S.top(); S.pop();
   for(i=0; i<list[u].size(); i++){
     v = list[u][i];
     if(color[v] == -1){
       color[v] = c;
       S.push(v);
     }
   }
 }
}
 
void assigncolor(){
 int id = 1;
 for(i=0; i<num; i++){
   color[i] = -1;
 }
 for(i=0; i<num; i++){
   if(color[i] == -1)
     dfs(i, id++);
 }
}
 
int main(){
 int a, b, trial, start, goal, kaisuu;
 cin >> num >>kaisuu;
 
 for(i=0; i<kaisuu; i++){
   scanf_s("%d %d", &a, &b);
   list[a].push_back(b);
   list[b].push_back(a);
 }

 assigncolor();

 cin >> trial;

 for(i=1; i<=trial; i++){
   scanf_s("%d %d", &start, &goal);
   if(color[start] == color[goal]){  
     cout << "yes" << endl;
   } else{
     cout << "no" << endl;
   }
 }
 
 return 0;
}

C++: #include <cstdio>
#include <algorithm>
#include <vector>

using namespace std;

struct UnionFindTree {
    size_t n;
    vector<int> tree;
    UnionFindTree(size_t n): n(n) {
        tree = vector<int>(n, -1);
    }
    int find_root(size_t v) {
        if (tree[v] < 0) return v;
        return tree[v] = find_root(tree[v]);
    }
    bool unite(size_t x, size_t y) {
        x = find_root(x);
        y = find_root(y);
        if (x == y) return false;
        if (rank(x) < rank(y)) swap(x, y);
        tree[x] += tree[y];
        tree[y] = x;
        return true;
    }
    bool has_same_root(size_t x, size_t y) {
        return find_root(x) == find_root(y);
    }
    size_t rank(size_t v) {
        return -tree[find_root(v)];
    }
};

int main() {
    size_t n, m;
    scanf("%zu %zu", &n, &m);

    UnionFindTree tree(n);
    for (size_t i=0; i<m; ++i) {
        size_t s, t;
        scanf("%zu %zu", &s, &t);

        tree.unite(s, t);
    }

    size_t q;
    scanf("%zu", &q);

    for (size_t i=0; i<q; ++i) {
        size_t s, t;
        scanf("%zu %zu", &s, &t);

        printf("%s\n", tree.has_same_root(s, t)? "yes":"no");
    }

    return 0;
}

C++: #include <bits/stdc++.h>
#include <sstream>
using namespace std;
int arr[100005];
int find(int index){
	while(1){
		if(arr[index]==-1)
			break;
		else
			index=arr[index];
	}
	return index;
}
int main(){
	ios::sync_with_stdio(0);cin.tie(0); 
	int n,m,a,b;
	cin >> n >> m;
	for(int i=0;i<=n;i++){
		arr[i]=-1;
	}
	while(m--){
		cin >> a >> b;
		int tmp1=find(a);
		int tmp2=find(b);
		if(tmp1!=tmp2){
			arr[tmp2]=tmp1;
		}
	}
	
	int q;
	cin >> q;
	while(q--){
		cin >> a >> b;
		if(find(a)==find(b)){
			cout << "yes" << endl;
		}
		else{
			cout << "no" << endl;
		}
 	}
	return 0;
}

C++: #include<iostream>
#include<vector>
#include<stack>
#include<queue>
#include<algorithm>
#include<ctime>

void dfs(std::vector<std::vector<int> > &n) {
	int question;
	std::cin >> question;

	for (int i = 0; i < question; i++) {
		int from, to;
		std::cin >> from >> to;
		std::stack<int> s;
		std::vector<std::vector<int> > went(n.size(), std::vector<int>(n.size(), 0));
		s.push(from);
		bool flag = false;
		while (s.size() != 0 && flag == false){
			int num = s.top(); s.pop();
			for (size_t j = 0; j < n[num].size(); j++) {
				if (n[num][j] == to) {
					flag = true;
					break;
				}
				if (went[num][j] == 0) {
					s.push(n[num][j]);
					went[num][j] = 1;
				}
			}
		}
		if (flag) {
			std::cout << "yes" << std::endl;
		} else {
			std::cout << "no" << std::endl;
		}
	}
}

int main() {
	int people, relation;

	std::cin >> people >> relation;

	std::vector<std::vector<int> > n(people);

	for (int i = 0; i < relation; i++) {
		int from, to;
		std::cin >> from >> to;
		n[from].push_back(to);
		n[to].push_back(from);
	}

	dfs(n);

	return 0;
}

C++: #include<iostream>
#include<vector>
#include<limits.h>
#include<stack>
#include<string>
using namespace std;

vector< vector<int> > L(100005);
int c[100005]={};

void dfs (int v, int marker){
	if(c[v]!=0){
		return;
	}
	c[v]=marker;
	for (int i=0;i<L[v].size();i++){
		dfs(L[v][i],marker);
	}
}

int main(){
	ios::sync_with_stdio(false);
	cin.tie(0);
	
	int n,m,a,b,q,s,t;
	cin >> n >> m;
	
	for (int i=0;i<m;i++){
		cin >> a >> b;
		L[a].push_back(b);
	}
	
	int marker=1;
	for (int i=0;i<n;i++){
		if (c[i]==0){
			dfs(i,marker);
			marker++;
		}
	}
	
	
	cin >> q;
	int d[2][q];
	for (int i=0;i<q;i++){
		cin >> d[i][0];
		cin >> d[i][1]; 
	}
	for (int i=0;i<q;i++){
		if(c[d[i][0]]==c[d[i][1]]){
			cout << "yes" << endl;
		}else{
			cout << "no" << endl;
		}
	}
	
	out(c);
	return 0;
}

C++: #include <iostream>
#include <vector>
#include <cstring>
using namespace std;

const int MAX = 100005;
const int NIL = -1;
int n;
vector<int> G[MAX];
int color[MAX];


void dfs(int r, int c) {
  color[r] = c;
  for (int u: G[r]) {
    if (color[u] == NIL) {
      dfs(u, c);
    }
  }
}

int main() {
  int m, s, t, q;
  cin >> n >> m;
  for (int i = 0; i < m; i++) {
    cin >> s >> t;
    G[s].push_back(t);
    G[t].push_back(s);
  }
  int color_id {0};
  memset(color, NIL, sizeof color);
  for (int i = 0; i < n; i++) {
    if (color[i] == NIL) {
      dfs(i, color_id++);
    }
  }

  cin >> q;
  for (int i = 0; i < q; i++) {
    cin >> s >> t;
    if (color[s] == color[t]) {
      cout << "yes" << endl;
    } else {
      cout << "no" << endl;
    }
  }
  return 0;
}