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
}

Python: #!/usr/bin/python3
n, m = map(int, input().split())
ALL = [0] * n
Graph = []
for i in range(m):
    s, t = map(int, input().split())
    if ALL[s] == 0 and ALL[t] == 0:
        Graph.append(set([s, t]))
    elif ALL[s] == 0:
        for g in Graph:
            if t in g:
                g.add(s)
                break
    elif ALL[t] == 0:
        for g in Graph:
            if s in g:
                g.add(t)
                break
    else:
        sg = None
        tg = None
        for g in Graph:
            if s in g:
                sg = g
            if t in g:
                tg = g

        if sg is not tg:
            sg.update(tg)
            Graph.remove(tg)

    ALL[s] = 1
    ALL[t] = 1
q = int(input())
for i in range(q):
    s, t = map(int, input().split())
    for g in Graph:
        if s in g and t in g:
            print('yes')
            break
    else:
        print('no')

Python: def tan(G,st,fi):
    for i in range(len(G)):
        if G[st][i] == 1:
            if i == fi:
                return 1
            tan(G,i,fi)
    
n,m = list(map(int, input().split()))
G = [[0 for i in range(n)] for j in range(n)]

for i in range(m):
    S = list(map(int, input().split()))
    G[S[0]][S[1]] = 1

q = int(input())
ans = []
for i in range(q):
    Q = list(map(int, input().split()))
    st = Q[0]
    fi = Q[1]
    if(tan(G,Q[0],Q[1])):
        ans.append("yes")
    else:
        ans.append("no")
        
for i in range(q):
    print(ans[i])

Python: def bfs(adj, s):
    n = len(adj)
    d = [-1 for _ in range(n)]
    c = [0 for _ in range(n)]

    d[s] = 0
    c[s] = 1

    queue = [s]

    while len(queue) > 0:
        u = queue.pop(0)
        for v in adj[u]:
            if c[v] == 0:
                c[v] = 1
                d[v] = d[u] + 1
                queue.append(v)

    return d


s = [int(x) for x in input().split()]
n = s[0]
m = s[1]
adj = [[] for _ in range(n)]
for _ in range(m):
    s = [int(x) for x in input().split()]
    adj[s[0]].append(s[1])
    adj[s[1]].append(s[0])

q = int(input())
for _ in range(q):
    s = [int(x) for x in input().split()]
    u = s[0]
    v = s[1]
    d = bfs(adj, u)
    if d[v] > 0:
        print("yes")
    else:
        print("no")

Python: from collections import deque

def bfs(graph, start):
    visited = {start: None}
    unvisited = deque()
    unvisited.append(start)
    while unvisited:
        now = unvisited.popleft()
        for next in graph[now]:
            if not (next in visited):
                unvisited.append(next)
                visited[next] = now
    return  visited                                

n, m = map(int, input().split())
g = [set() for _ in range(n)]
group = []

for i in range(m):
    a, b = map(int, input().split())
    g[a].add(b)
    g[b].add(a)

q = int(input())

for i in range(q):
    s, t = map(int, input().split())
    for j in range(len(group)):
        if s in group[j] and t in group[j]:
            print('yes')
            break
        elif s in group[j]:
            print('no')
            break
    
    else:
        group_tmp = set(bfs(g, s).keys())
        if t in group_tmp:
            print('yes')
        else:
            print('no')
        group.append(group_tmp)

Python: 
NIL = -1

def assignColor():
    id = 1
    for i in range(n):
        color[i] = NIL
    for u in range(n):
        if color[u] == NIL:
            dfs(u, id)
            id += 1

def dfs(r, c):
    S = []
    S.append(r)
    color[r] = c
    while S:
        u = S.pop()
        for v in (G[u]):
            if color[v] == NIL:
                color[v] = c
                S.append(v)


nums=list(map(int,input().split()))
n = nums[0]
m = nums[1]
G = []
color = [NIL] * n

for i in range(n):
    G.append(set())
    
for i in range(m):
    nodes=list(map(int,input().split()))
    G[nodes[0]].add(nodes[1])
    G[nodes[1]].add(nodes[0])

assignColor()

q = int(input())
for i in range(q):
    questions=list(map(int,input().split()))
    if color[questions[0]] == color[questions[1]]:
        print("yes")
    else:
        print("no")

Python: def BFS(s = 0, group_num = 0):
    Q.pop(0)
    color[s] = 2
    for j in range(len(A[s])):
        if color[A[s][j]] == 0:
            Q.append(A[s][j])
            color[A[s][j]] = 1
            affil[A[s][j]] = group_num
    if len(Q) != 0:
        BFS(Q[0], group_num)

entry = map(int, raw_input().split())
n = entry[0]
m = entry[1]

A = range(n)
for i in A:
    A[i] = list()
for i in range(m):
    entry = map(int, raw_input().split())
    s = entry[0]
    t = entry[1]
    A[s].append(t)
    A[t].append(s)

color = [0] * n
affil = [0] * n
group_num = -1
for i in range(n):
    if color[i] == 0:
        Q = [i]
        group_num = group_num + 1
        affil[i] = group_num
        BFS(i, group_num)

q = int(raw_input())
for i in range(q):
    entry = map(int, raw_input().split())
    if affil[entry[0]] == affil[entry[1]]:
        print("yes")
    else:
        print("no")

Python: def tan(G,st,fi):
    global flag
    for i in range(len(G)):
        if G[st][i] == 1:
            if i == fi:
                flag = 1
            tan(G,i,fi)
    
n,m = list(map(int, input().split()))
G = [[0 for i in range(n)] for j in range(n)]

for i in range(m):
    S = list(map(int, input().split()))
    G[S[0]][S[1]] = 1
    G[S[1]][S[0]] = 1

q = int(input())
ans = []
for i in range(q):
    Q = list(map(int, input().split()))
    if Q[0]<Q[1]:
        st = Q[0]
        fi = Q[1]
    else:
        st = Q[1]
        fi = Q[0]

    flag = 0
    tan(G,st,fi)
    if flag==1:
        ans.append("yes")
    else:
        ans.append("no")
        
for i in range(q):
    print(ans[i])