Go: package main

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

const (
	MAX = 100000
	NIL = -1
)

var (
	n     int
	G     [MAX][]int
	color [MAX]int
)

func DFS(r int, c int) {
	S := list.New()
	S.PushFront(r)
	color[r] = c
	for S.Len() != 0 {
		u := S.Remove(S.Front()).(int)
		for i := 0; i < len(G[u]); i++ {
			v := G[u][i]
			if color[v] == NIL {
				color[v] = c
				S.PushFront(v)
			}
		}
	}
}

func assignColor() {
	id := 1
	for i := 0; i < n; i++ {
		color[i] = NIL
	}
	for i := 0; i < n; i++ {
		if color[i] == NIL {
			id++
			DFS(i, id)
		}
	}
}

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

	assignColor()
	scanner.Scan()
	q, _ = strconv.Atoi(scanner.Text())
	for i := 0; i < q; i++ {
		scanner.Scan()
		s, _ = strconv.Atoi(scanner.Text())
		scanner.Scan()
		t, _ = strconv.Atoi(scanner.Text())
		if color[s] == color[t] {
			fmt.Println("yes")
		} else {
			fmt.Println("no")
		}
	}
}

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

using namespace std;

static const int MAX = 100000;
static const int NIL = -1;

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

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 (int i = 0; i < G[u].size(); i++) {
            int v = G[u][i];
            if (color[v] == NIL) {
                color[v] = c;
                S.push(v);
            }
        }
    }
}

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

int main()
{
    int s, t, m, q;
    int i;

    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]) {
            cout << "yes" << endl;
        } else {
            cout << "no" << endl;
        }
    }

    return 0;
}

C++: #include <iostream>
#include <vector>
#include <stack>
using namespace std;
static const int MAX = 100000;
static const int NIL = -1;

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

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(int i=0; i<G[u].size(); i++){
            int v = G[u][i];
            //printf("G[%d][%d] = %d color[%d] = %d\n", u, i, G[u][i], v, color[v]);
            if(color[v] == NIL){
                color[v] = c;
                S.push(v);
            }
        }
    }
}

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

int main(){
    int s, t, m, q;
    
    cin >> n >> m;
    
    for(int i=0; i<m; i++){
        cin >> s >> t;
        G[s].push_back(t);
        G[t].push_back(s);
    }
    
    assignColor();
    
    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;
}

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<cstdio>
#include<queue>
#include<vector>
using namespace std;

vector<int> ad[100000];
vector<int> v,d;

int main()
{
	int i,j,n,m,a,b,q,l,k;
	queue<int> Q;
	
	cin >> n;
	cin >> m;
	for(i=0;i<=m-1;i++)
	{
		cin >> a;
		cin >> b;
		ad[a].push_back(b);
		ad[b].push_back(a);
	}
	for(i=0;i<=n-1;i++) 
	{
		ad[i].push_back(-1);
		v.push_back(0);
		d.push_back(-1);
	}
	j=0;
	for(i=0;i<=n-1;i++)
	{
		if(v[i]==0)
		{
			Q.push(i);
			v[i]=1;
			d[i]=j;
			while(Q.empty()!=1)
			{
				l=Q.front();
				for(k=0;ad[l][k]!=-1;k++)
				{
					if(v[ad[l][k]]==0)
					{
						Q.push(ad[l][k]);
						v[ad[l][k]]=1;
						d[ad[l][k]]=j;
					}
				}
				Q.pop();
			}
			j++;
		}
	}
	cin >> q;
	for(i=0;i<=q-1;i++)
	{
		cin >> a;
		cin >> b;
		if(d[a]==d[b]) cout << "yes" << endl;
		else cout << "no" << endl;
	}
	return 0;
}

C++: /*
 * ALDS1_11_D.cpp
 *
 *  Created on: May 8, 2018
 *      Author: 13743
 */

#include<iostream>
#include<vector>

using namespace std;

bool visited[100000];

void dfsRec(vector<int>* a, int v) {
	if(visited[v]) return;
	visited[v] = 1;
	for(int &x:a[v]) {
		dfsRec(a, x);
	}
}

int main() {
	int n, m;
	vector<int> adj[100000];

	cin >> n >> m;
	int u, v;
	for(int i=0; i<m; i++) {
		cin >> u >> v;
		adj[u].push_back(v);
		adj[v].push_back(u);
	}

	int q;
	cin >> q;
	while(q--) {
		for(int i=0; i<n; i++) {
			visited[i] = 0;
		}
		cin >> u >> v;
		dfsRec(adj, u);
		(visited[v]) ? printf("yes\n") : printf("no\n");
	}
}

C++: #include <iostream>
#include <string>
#include <stack>
#include <queue>
#include <vector>
#include <list>
#include <set>
#include <map>
#include <algorithm>

#include <cstdio>

using namespace std;
#define rep(i, n) for (int i = 0; i < (n); i++)
#define repc(i, s, n) for (int i = (s); i <= (n); i++)
#define rrep(i, n) for (int i = (n) - 1; i >= 0; i--)
#define rrepc(i, s, n) for (int i = (s); i >= (n); i--)
#define print_array(ary, size) cout << ary[0]; rep1(i, 1, size - 1) cout << ' ' << ary[i]; cout << endl;
typedef long long ll;
typedef unsigned long long ull;

vector<int> SNS[100000];
int Group[100000] = { 0 };

int main()
{
	int n, m, q, s, t;
	int man1, man2;
	int grNo = 1;
	int current, next;
	queue<int> Q;
	vector<int>::iterator it;
	
	cin >> n >> m;
	rep(i, m) {
		cin >> man1 >> man2;
		SNS[man1].push_back(man2);
		SNS[man2].push_back(man1);
	}

	rep(i, n) {
		if (Group[i] == 0) {
			Q.push(i);
			Group[i] = grNo;

			while (!Q.empty()) {
				current = Q.front();

				for (it = SNS[current].begin(); it != SNS[current].end(); it++) {
					next = *it;
					if (Group[next] == 0) {
						Q.push(next);
						Group[next] = grNo;
					}
				}

				Q.pop();
			}

			grNo++;
		}
	}

	cin >> q;
	rep(i, q) {
		cin >> s >> t;
		if (Group[s] == Group[t]) cout << "yes" << endl;
		else cout << "no" << endl;
	}

	return 0;
}

C++: #include <stdio.h>
int ancestor[10];
int find(int x){
    if(ancestor[x]==x)return x;
    return ancestor[x]=find(ancestor[x]);
}
int min(int a,int b){
    if(a<b)return a;
    return b;
}
int max(int a,int b){
    if(a>b)return a;
    return b;
}
int main(){
    int n,q,m,temp,x,y;
    scanf("%d%d",&n,&m);
    for(int i=0;i<n;i++)ancestor[i]=i;
    for(int i=0;i<m;i++){
        scanf("%d%d",&x,&y);
        temp=find(x);
        q=find(y);
        ancestor[max(temp,q)]=min(temp,q);
    }
    scanf("%d",&q);
    for(int i=0;i<q;i++){
        scanf("%d%d",&x,&y);
        if(find(x)!=find(y))printf("no\n");
        else printf("yes\n");
    }
}