Go: package main

import (
	"fmt"
	"bufio"
	"os"
	"strconv"
)

func main() {
	var n,m int
	fmt.Scan(&n)
	group := make([]int, n)
	for i := 0; i < n; i++ {
		group[i] = i
	}
	
	fmt.Scan(&m)
	sc := bufio.NewScanner(os.Stdin)
	sc.Split(bufio.ScanWords)
	for i := 0; i < m; i++ {
		sc.Scan()
		s, _ := strconv.Atoi(sc.Text())
		sc.Scan()
		t, _ := strconv.Atoi(sc.Text())

		if group[s] < group[t] {
			group[t] = group[s]
		} else {
			group[s] = group[t]
		}
	}

	sc.Scan()
	q, _ := strconv.Atoi(sc.Text())
	for i := 0; i < q; i++ {
		sc.Scan()
		s, _ := strconv.Atoi(sc.Text())
		sc.Scan()
		t, _ := strconv.Atoi(sc.Text())

		if root(s, &group) == root(t, &group) {
			fmt.Println("yes")
		} else {
			fmt.Println("no")
		}
	}
}

func root(i int, group *[]int) int {
	if i == (*group)[i] {
		return i
	}
	(*group)[i] = root((*group)[i], group)
	return (*group)[i]
}

C++: #include<iostream>
#include<vector>
#inlcude<stack>
using namespace std;
#define MAX 100000
#define NIL -1

int n, color[MAX];
vector<int> G[MAX];


void dfs(int r, int c) {
  stack<int> S;
  int i, v, u;
  S.push(r);
  color[r]=c;
  while (! S.empty()) {
    u=S.top();
    S.pop();
    for (i=0; i<G[u].size(); i++) {
        v=G[u][i];
      if (color[v]==NIL) {
        color[v]=c;
        S.push(v);
      }
    }
  }
}



void assignColor() {
  int i, u;
  int id=1;
  for (i=0; i<n; i++) color[i]=NIL;
  for (u=0; u<n; u++) {
    if (color[u]==NIL)
      dfs(u, id++);
  }
}

int main() {

  int  m, i, j, v, s, t, q;

  cin >> n >> m;

  for (i=0; i<m; i++) {
    cin >> s >> t;
    G[s].push_back(t);
    G[t].push_back(s);
  }

  assignColor();

  cin >> q;

  for (i=0; i<q; i++) {
    cin >> s >> t;
    if (color[s]== color[t]) {
      printf("yes\n");
    } else {
      printf("no\n");
    }
  }

  return 0;

}

C++: #include<bits/stdc++.h>
using namespace std;
int par[100005];
int ra[100005];
void init(int n){
  for(int i=0;i<n;i++){
    par[i]=i;
    ra[i]=0;
  }
}
int find(int x){
  if(par[x]==x){
    return x;
  }
  else{
    return par[x]=find(par[x]);
  }
}
void unite(int x,int y){
  x=find(x);
  y=find(y);
  if(x==y)return;
  if(ra[x]<ra[y]){
    par[x]=y;
  }
  else{
    par[y]=x;
    if(ra[x]==ra[y])ra[x]++;
  }
}
bool same(int x,int y){
  return find(x)==find(y);
}

int main(){
  int n,m;
  cin >> n >> m;
  init(n);
  for(int i=0;i<m;i++){
    int a,b;
    cin >> a >> b;
    unite(a,b);
  }
  int q;
  cin >> q;
  for(int i=0;i<q;i++){
    int a,b;
    cin >> a >> b;
    if(same(a,b))cout << "yes" << endl;
    else cout << "no" << endl;
  }
  return 0;
}

C++: #include<bits/stdc++.h>

using namespace std;
const int maxn=100000+5;

int fa[maxn];
int V,E;
void init(){
    for(int i=1;i<=V;i++)
        fa[i]=i;
}

int find(int x){
    int y=fa[x];
    for(;fa[y]!=y;y=fa[y]);
    while(x!=y){
        int temp=fa[x];
        fa[x]=y;
        x=temp;
    }
    return y;
}

void merge(int x,int y){
    int nx=find(x);
    int ny=find(y);
    if(nx!=ny){
        fa[nx]=ny;
    }
}
int main(){
    cin>>V>>E;
    init();
    while(E--){
        int in,out;
        cin>>in>>out;
        merge(in,out);
    }
    int T;
    cin>>T;
    while(T--){
        int x,y;
        cin>>x>>y;
        if(find(x)!=find(y)) cout<<"no"<<endl;
        else cout<<"yes"<<endl;
    }
}

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

int x[100000][100];
bool y[100000];
int z[100000];

int main(){
	int n,m,a,b,q;
	cin>>n>>m;
	for(int i=0;i<m;i++){
		cin>>a>>b;
		x[a][z[a]]=b;
		x[b][z[b]]=a;
		z[a]++;
		z[b]++;
	}
	cin>>q;
	for(int h=0;h<q;h++){
		cin>>a>>b;
		memset(y,0,sizeof(y));
		y[a]=true;
		for(int i=0;i<20;i++){
			for(int j=0;j<n;j++){
				if(y[j]==true){
					for(int k=0;k<z[j];k++){
						y[x[j][k]]=true;
					}
				}
				if(y[b]==true){
					cout<<"yes"<<endl;
					goto Exit;
				}
			}
		}
		cout<<"no"<<endl;
		Exit:;
	}
	return 0;
}

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

void boo(int b[], int y[], int w, int m){
	for(int i = 0; i < m; i++){
		if(b[i] == w) {
			if(y[b[i + m]] != -1)
				y[b[i + m]] = 1;
		}
	}
	for(int i = m; i < m * 2; i++){
		if(b[i] == w) {
			if(y[b[i - m]] != -1)
				y[b[i - m]] = 1;
		}
	}
}

int foo(int a, int s, int b[], int m, int n){
	int z = 0, y[100100] = {}, k = 1;
	y[a] = 1;
	while(k){
		k = 0;
		for(int i = 0; i < n; i++){
			if(y[i] == 1){ 
				if(i == s){
					z = 1;
					k = 0;
					break;
				}
				k = 1;
				y[i] = -1;
				boo(b, y, i, m);
				
				
			}
		}
	}
	return z;
	
}


int main(){
	int b[200100];
	int n, m, q, a, s;
	int i, j, k;
	cin>>n>>m;
	for(i = 0; i < m; i++){
		cin>>b[i]>>b[m + i];
	}

	cin>>q;

	for(i = 0; i < q; i++){
		cin>>a>>s;
		if(foo(a, s, b, m, n) == 1){
			cout<<"yes"<<endl;
		} else {
			cout<<"no"<<endl;
		}
	}
	
	return 0;
}