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 <iostream>
#include <vector>
#include <queue>

using namespace std;

const int kSize = 100001;

vector<int> adj[kSize];
bool isMarked[kSize];
int d[kSize];
int cc = 0;

void dfs(int v) {
    isMarked[v] = true;
    d[v] = cc;

    for (int i = 0; i < adj[v].size(); ++i) {
        int u = adj[v][i];
        if (!isMarked[u]) {
            dfs(u);
        }
    }
}

int main() {
    int n, m;
    fill(isMarked, isMarked + kSize, false);
    cin >> n >> m;
    for (int i = 0; i < m; ++i) {
        int from, to;
        cin >> from >> to;
        adj[from].push_back(to);
        adj[to].push_back(from);
    }

    for (int i = 0; i < n; ++i) {
        if (!isMarked[i]) {
            dfs(i);
            cc++;
        }
    }

    int q;
    cin >> q;
    for (int i = 0; i < q; ++i) {
        int from, to;
        cin >> from >> to;
        if (d[from] == d[to]) {
            cout << "yes";
        } else {
            cout << "no";
        }
        cout << endl;
    }
    return 0;
}

C++: #include <iostream>
#include <vector>
#include <numeric>
#include <algorithm>
#include <unordered_set>

using namespace std;

const int N_MAX = 100000;
vector<vector<int32_t>> A(N_MAX);
vector<bool> visited(N_MAX);
vector<int32_t> deadend;

void dfs1(int32_t u) {
    visited[u] = true;

    for (int32_t v : A[u]) {
        if (!visited[v]) {
            dfs1(v);
        }
    }

    deadend.push_back(u);

    return;
}

unordered_set<int32_t> dfs2(int32_t u, unordered_set<int32_t> &scc) {
    visited[u] = true;

    for (int32_t v : A[u]) {
        if (!visited[v]) {
            dfs2(v, scc);
        }
    }

    scc.insert(u);

    return scc;
}

int main() {
    fill(visited.begin(), visited.end(), false);

    int32_t n, m;
    cin >> n >> m;

    for (int32_t i = 0; i < m; i++) {
        int32_t s, t;
        cin >> s >> t;

        A[s].push_back(t);
        A[t].push_back(s);
    }

    for (int32_t i = 0; i < n; i++) {
        if (!visited[i]) {
            dfs1(i);
        }
    }

    reverse(deadend.begin(), deadend.end());
    fill(visited.begin(), visited.end(), false);
    vector<unordered_set<int32_t>> sccs;

    for (int32_t u : deadend) {
        if (!visited[u]) {
            unordered_set<int32_t> scc;
            dfs2(u, scc);
            sccs.push_back(scc);
        }
    }

    int32_t q;
    cin >> q;

    for (int32_t i = 0; i < q; i++) {
        int32_t s, t;
        cin >> s >> t;

        bool flag = false;
        for (auto scc : sccs) {
            if (scc.find(s) != scc.end() && scc.find(t) != scc.end()) {
                flag = true;
                break;
            }
        }

        cout << (flag ? "yes" : "no") << endl;
    }

    return 0;
}