Go: package main

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

// Node 頂点
type Node struct {
	gid  int   // グループID
	edge []int // 隣接辺
}

// NoID グループIDなし
const NoID = -1

// NewNode 頂点の生成
func NewNode() *Node {
	return &Node{gid: NoID, edge: []int{}}
}

func parseNode(nodes []*Node, gid int, queue []int) {
	if len(queue) == 0 {
		return
	}
	var nextQ []int
	for _, id := range queue {
		node := nodes[id]
		if node.gid == NoID {
			node.gid = gid
			for _, edge := range node.edge {
				nextQ = append(nextQ, edge)
			}
		}
	}
	parseNode(nodes, gid, nextQ)
	return
}
func digNode(nodes []*Node, id, gid int) {
	node := nodes[id]
	if node.gid != NoID {
		// 探索済み
		return
	}
	node.gid = gid
	for _, edge := range node.edge {
		digNode(nodes, edge, gid)
	}
	return
}

func main() {
	scanner := bufio.NewScanner(os.Stdin)
	n, m := eGetInt2(scanner)

	nodes := make([]*Node, n)
	for i := 0; i < n; i++ {
		nodes[i] = NewNode()
	}

	for i := 0; i < m; i++ {
		a, b := eGetInt2(scanner)
		nodes[a].edge = append(nodes[a].edge, b)
		nodes[b].edge = append(nodes[b].edge, a)
	}

	for i := 0; i < n; i++ {
		// 幅優先探索
		// gid := i
		// queue := []int{i}
		// parseNode(nodes, gid, queue)

		// 深さ優先探索
		digNode(nodes, i, i)
	}

	q := eGetInt(scanner)
	for i := 0; i < q; i++ {
		a, b := eGetInt2(scanner)
		if nodes[a].gid == nodes[b].gid {
			fmt.Println("yes")
		} else {
			fmt.Println("no")
		}
	}
}

func eGetInt(scanner *bufio.Scanner) int {
	t := eAtoi(strings.Fields(eGetline(scanner)))
	return t[0]
}
func eGetInt2(scanner *bufio.Scanner) (int, int) {
	t := eAtoi(strings.Fields(eGetline(scanner)))
	return t[0], t[1]
}

func eGetline(p *bufio.Scanner) string {
	if !p.Scan() {
		if err := p.Err(); err != nil {
			log.Fatal(err.Error())
		}
		return ""
	}
	return p.Text()
}

func eAtoi(s []string) []int {
	ints := make([]int, len(s))
	var err error
	for i, e := range s {
		ints[i], err = strconv.Atoi(e)
		if err != nil {
			log.Fatal(err.Error())
		}
	}
	return ints
}

C++: #include <bits/stdc++.h>
using ll = long long;
using namespace std;
#define _overload3(_1, _2, _3, name, ...) name
#define _rep(i, n) repi(i, 0, n)
#define repi(i, a, b) for(int i = int(a); i < int(b); ++i)
#define rep(...) _overload3(__VA_ARGS__, repi, _rep, )(__VA_ARGS__)
const long long INFLL = 1LL << 60;
const int INFINT = 1 << 30;
const long long MOD = 1e9 + 7;

vector<vector<int>> G(101, vector<int>(0));
vector<int> c(101, 0);
vector<int> d(101, 0);
vector<int> f(101, 0);

template <class T> using vec_alias = ::std::vector<T>;

template <class T> void vecout(T V) {
    auto t = V.begin();
    while(t != V.end()) {
        cout << " " << *t++;
        // if(t != V.end()) cout << " ";
    }
    cout << endl;
};

int t = 0;
void dfs(int i) {
    if(c[i]) return;
    c[i] = 1;
    d[i] = ++t;
    for(auto e : G[i])
        dfs(e);
    f[i] = ++t;
}

class node {
  public:
    int dist = -1;
    vector<int> nex;
};

template <template <class> class Container> class union_find {
  protected:
    class node_type;

  public:
    using container_type = Container<node_type>;
    using size_type = typename container_type::size_type;

  protected:
    class node_type {
      public:
        typename union_find::size_type parent;
        typename union_find::size_type size;
    };

    container_type tree;

  public:
    union_find() : tree() {}
    explicit union_find(const size_type size) : tree(size, {0, 1}) {
        for(size_type i = 0; i < size; ++i)
            tree[i].parent = i;
    }

    bool empty() const { return tree.empty(); }
    size_type size() const { return tree.size(); }

    size_type find(size_type x) {
        assert(x < size());
        while(tree[x].parent != x)
            x = tree[x].parent = tree[tree[x].parent].parent;
        return x;
    }
    bool same(const size_type x, const size_type y) {
        assert(x < size());
        assert(y < size());
        return find(x) == find(y);
    }
    size_type size(const size_type x) {
        assert(x < size());
        return tree[find(x)].size;
    }

    ::std::pair<size_type, size_type> unite(size_type x, size_type y) {
        assert(x < size());
        assert(y < size());
        x = find(x);
        y = find(y);
        if(x != y) {
            if(tree[x].size < tree[y].size) ::std::swap(x, y);
            tree[x].size += tree[y].size;
            tree[y].parent = x;
        }
        return {x, y};
    }
};

int main() {
    cin.tie(0);
    ios::sync_with_stdio(false);
    int n, m, q, s, t;
    cin >> n >> m;
    union_find<vec_alias> uf(n);
    rep(i, m) {
        cin >> s >> t;
        uf.unite(s, t);
    }
    cin >> q;
    rep(i, q) {
        cin >> s >> t;
        cout << (uf.same(s, t) ? "yes" : "no") << "\n";
    }
}

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;

  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<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();
    int i;

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

void ass(){
  int id=1;
  int i,u;

  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 s,t,m,q;

  cin>>n>>m;

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

  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;
}