Go: package main

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

// I/O
type Scanner struct {
	sc *bufio.Scanner
}

func NewScanner() *Scanner {
	sc := bufio.NewScanner(os.Stdin)
	sc.Split(bufio.ScanWords)
	sc.Buffer(make([]byte, 1024), int(1e+9))
	return &Scanner{sc}
}

func (s *Scanner) nextStr() string {
	s.sc.Scan()
	return s.sc.Text()
}

func (s *Scanner) nextInt() int {
	i, e := strconv.Atoi(s.nextStr())
	if e != nil {
		panic(e)
	}
	return i
}

func (s *Scanner) nextFloat() float64 {
	f, e := strconv.ParseFloat(s.nextStr(), 64)
	if e != nil {
		panic(e)
	}
	return f
}

func (s *Scanner) nextRuneSlice() []rune {
	return []rune(s.nextStr())
}

func (s *Scanner) nextIntSlice(n int) []int {
	res := make([]int, n)
	for i := 0; i < n; i++ {
		res[i] = s.nextInt()
	}
	return res
}

func (s *Scanner) nextFloatSlice(n int) []float64 {
	res := make([]float64, n)
	for i := 0; i < n; i++ {
		res[i] = s.nextFloat()
	}
	return res
}

// Arithmetic
func max(nums ...int) int {
	m := nums[0]
	for _, i := range nums {
		if m < i {
			m = i
		}
	}
	return m
}

func min(nums ...int) int {
	m := nums[0]
	for _, i := range nums {
		if m > i {
			m = i
		}
	}
	return m
}

func abs(x int) int {
	if x > 0 {
		return x
	}
	return -x
}

func pow(x, y int) int {
	res := 1
	for i := 0; i < y; i++ {
		res *= x
	}
	return res
}

func ceil(a, b int) int {
	if a%b == 0 {
		return a / b
	} else {
		return a/b + 1
	}
}

// Sort
type RuneSlice []rune

func (a RuneSlice) Len() int           { return len(a) }
func (a RuneSlice) Less(i, j int) bool { return a[i] < a[j] }
func (a RuneSlice) Swap(i, j int)      { a[i], a[j] = a[j], a[i] }

// Main
func main() {
	sc := NewScanner()
	wtr := bufio.NewWriter(os.Stdout)
	N, M := sc.nextInt(), sc.nextInt()
	G := make([][]int, N)
	for i := 0; i < M; i++ {
		s, t := sc.nextInt(), sc.nextInt()
		G[s] = append(G[s], t)
		G[t] = append(G[t], s)
	}
	group := make([]int, N)
	for i := 0; i < N; i++ {
		group[i] = -1
	}
	var dfs func(cur int)
	dfs = func(cur int) {
		for i := 0; i < len(G[cur]); i++ {
			next := G[cur][i]
			if group[next] == -1 {
				group[next] = group[cur]
				dfs(next)
			}
		}
	}
	num := 0
	for i := 0; i < N; i++ {
		if group[i] == -1 {
			group[i] = num
			dfs(i)
			num++
		}
	}

	Q := sc.nextInt()
	for i := 0; i < Q; i++ {
		s, t := sc.nextInt(), sc.nextInt()
		if group[s] == group[t] {
			fmt.Fprintln(wtr, "yes")
		} else {
			fmt.Fprintln(wtr, "no")
		}
	}
	wtr.Flush()
}

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

using namespace std;

static const int MAX = 100000;

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

void dfs (int r, int c) {

    int i, u, v;

    stack<int> S;
    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] == -1) {
                color[v] = c;
                S.push(v);
            }
        }
    }

}

void assignColor () {

    int id = 1, i, u;

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

}

int main () { 

    int s, t, m, q, 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<cstdio>
#include<queue>

using namespace std;

static const int N = 100000;

int m,n;

queue<int> Q[N];
int color[N];

void visit(int a,int c){
    color[a] = c;
   while( !(Q[a].size() == 0) ){
        int u = Q[a].front();
        if(color[u] == 0) visit(u,c);
        Q[a].pop();
    }
}

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

    for(int i=0; i<n; i++) color[i] = 0;

    for(int i=0; i<m;i++){
        int u,v;
        scanf("%d",&u);
        scanf("%d",&v);
        Q[u].push(v);
        Q[v].push(u);
    }
    
    int cc = 1;

    for(int i=0; i<n; i++){
        if(color[i] == 0){
            visit(i,cc);
            cc++;
        }
    }

    int l; 
    scanf("%d",&l);
    for(int i =0 ;i<l;i++){
        int x,y;
        scanf("%d",&x);
        scanf("%d",&y);

        if(color[x] == color[y]) printf("yes\n");
        else printf("no\n");

    }

}

C++: #include<iostream> 
#include <list> 
#define N 100001
using namespace std; 
int n, loop;
int color=0;

int flag[N];

bool *visited = new bool[N];

class Graph{ 
    int V; 
    list<int> *adj; 
  
public: 
    void DFSUtil(int v); 
    Graph(int V);  
    void addEdge(int v, int w); 
    void connectedComponents(); 
}; 
  
void Graph::connectedComponents() { 
    for(int v = 0; v < V; v++){
        visited[v] = false; 
	}
  
    for (int v=0; v<V; v++) { 
        if (visited[v] == false) {
        	color++;
            DFSUtil(v); 
        } 
    } 
}
  
void Graph::DFSUtil(int v) 
{ 
    visited[v] = true;
    flag[v]=color;
    list<int>::iterator i; 
    for(i = adj[v].begin(); i != adj[v].end(); ++i){
        if(!visited[*i]){
            DFSUtil(*i); 
		}
	}
} 
  
Graph::Graph(int V) { 
    this->V = V; 
    adj = new list<int>[V]; 
} 
  
void Graph::addEdge(int v, int w) { 
    adj[v].push_back(w); 
    adj[w].push_back(v); 
} 

int main() {
  	int i, x,y,uji,j;
  	cin>>n>>loop;
	Graph g(n);
	 
	
	
  	for(i=0; i<loop; i++){
		cin>>x>>y;
		g.addEdge(x,y);
	}
	
	for(j= 0; j < n; j++){
	   visited[j] = false; 
	   flag[j]=0;
	}
	g.connectedComponents();
	
	cin>>uji;
	int prev=-1;
	for(i=0; i<uji; i++){
		cin>>x>>y;
		
		if(flag[y]==flag[x]){
			cout<<"yes"<<endl;
		}else{
			cout<<"no"<<endl;
		}
		prev=x;
	}
    return 0; 
}

C++: #include <bits/stdc++.h>
using namespace std;
// #define int long long
using ll=long long;
using vi=vector<int>;
using vl=vector<long long>;
using pii=pair<int,int>;
using pll=pair<ll,ll>;
#define ITR(v,c) for(auto v=begin(c);v!=end(c);v++)
#define FORE(x,c) for(auto &x:c)
#define FOR(v,a,n) for(int v=a;v<(int)(n);v++)
#define REP(v,n) FOR(v,0,n)
#define RREP(v,n) for(int v=((int)(n)-1);v>=0;v--)
#define ALL(c) begin(c),end(c)
#define RALL(c) rbegin(c),rend(c)
#define SZ(c) ((int)c.size())
const int DX[9]={0,1,0,-1,1,1,-1,-1,0}, DY[9]={-1,0,1,0,-1,1,1,-1,0};
const int INF=1e9; const long long INFLL=1e18;
template<class T> ostream& operator << (ostream &os, const vector<T> &v) {
    ITR(i,v) os<<*i<<(i==end(v)-1?"":" "); return os; }
template<class T> istream& operator >> (istream &is, vector<T> &v) {
    ITR(i,v) is>>*i; return is; }
//------------------------------------------------------------------------------

//-------- Union Find
struct UnionFind {
	vector<int> data;
	UnionFind(int size) : data(size, -1) { }
    bool unionSet(int x, int y) {
	    x = root(x); y = root(y);
        if(x != y) {
            if(data[y] < data[x]) swap(x, y);
            data[x] += data[y]; data[y] = x;
        }
        return x != y;
	}
	bool findSet(int x, int y) {
	    return root(x) == root(y);
    }
	int root(int x) {
        return data[x] < 0 ? x : data[x] = root(data[x]);
    }
    int size(int x) {
        return -data[root(x)];
    }
};

signed main() {
    int n,m;
    cin>>n>>m;
    UnionFind uf(n);
    REP(i,m) {
        int a,b;
        cin>>a>>b;
        a--,b--;
        uf.unionSet(a,b);
    }

    int q;
    cin>>q;
    REP(i,q) {
        int a,b;
        cin>>a>>b;
        a--,b--;
        if(uf.root(a)==uf.root(b)) {
            cout<<"yes"<<endl;
        }
        else {
            cout<<"no"<<endl;
        }
    }
    return 0;
}