Go: package main

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

func getScanner(fp *os.File) *bufio.Scanner {
	scanner := bufio.NewScanner(fp)
	scanner.Split(bufio.ScanWords)
	scanner.Buffer(make([]byte, 500001), 500000)
	return scanner
}

func getNextString(scanner *bufio.Scanner) string {
	scanner.Scan()
	return scanner.Text()
}

func getNextInt(scanner *bufio.Scanner) int {
	i, _ := strconv.Atoi(getNextString(scanner))
	return i
}

func main() {
	fp := os.Stdin
	if len(os.Args) > 1 {
		fp, _ = os.Open(os.Args[1])
	}

	scanner := getScanner(fp)
	writer := bufio.NewWriter(os.Stdout)

	n := getNextInt(scanner)
	m := getNextInt(scanner)
	nodes := make([]Node, n)

	for i := 0; i < n; i++ {
		nodes[i].list = make([]int, 0)
	}

	for i := 0; i < m; i++ {
		s := getNextInt(scanner)
		t := getNextInt(scanner)
		nodes[s].list = append(nodes[s].list, t)
		nodes[t].list = append(nodes[t].list, s)
	}

	c := 1
	for i := 0; i < n; i++ {
		if nodes[i].c == 0 {
			traverse(nodes, i, c)
			c++
		}
	}

	q := getNextInt(scanner)

	for i := 0; i < q; i++ {
		s := getNextInt(scanner)
		t := getNextInt(scanner)
		if nodes[s].c == nodes[t].c {
			fmt.Fprintln(writer, "yes")
			continue
		}
		fmt.Fprintln(writer, "no")
	}

	writer.Flush()
}

// Node ...
type Node struct {
	list []int
	c    int
}

func traverse(nodes []Node, r, c int) {
	nodes[r].c = c
	for _, i := range nodes[r].list {
		if nodes[i].c != 0 {
			continue
		}
		traverse(nodes, i, c)
	}
}

Python: def DFS(s):
    flag[s] = 1
    group[j] += s
    for i in range(n):
        if G[s] == i and flag[i] == 0:
                DFS(i)
 

n, m = map(int, input().split())
G = [[] for j in range(n)]
for i in range(m):
    s, t = map(int, input().split())
    G[s] += t
    G[t] += s

flag = [0 for i in range(n)]
group = []
j = 0
for i in range(n):
    if flag[i] == 0:
        group.append([])
        DFS(i)
        j += 1

q = int(input())
ans = ["no" for i in range(q)]
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 gruop[j]:
            ans[i] = "yes"
for i in range(q):
    print(ans[i])

Python: import sys
sys.setrecursionlimit(10000)

def dfs(v):
    global node_chk
    global edge_chk
    global B
    global connect
    global value

    node_chk[v] = 1
    connect[v] = value
    for x in B[v]:
        if(node_chk[x] == 0):
                dfs(x)



n,m = map(int,input().split())
B = [[]for i in range(n)] # 隣接リスト
edge_chk = [[]for i in range(n)]
node_chk = [0 for i in range(n)]
connect = [0 for i in range(n)]
value = 0

for i in range(m):
    A = list(map(int,input().split()))
    B[A[0]].append(A[1])
    B[A[1]].append(A[0])
    edge_chk[A[0]].append(0)
    edge_chk[A[1]].append(0)

for i in range(n):
    if(node_chk[i] == 1):
        continue
    dfs(i)
    value += 1


q = int(input())
for i in range(q):
    start,target = map(int,input().split())
    if(connect[start] == connect[target]):
        print("yes")
    else:
        print("no")

Python: import sys
import os
import pprint

#fd = os.open('ALDS1_11_D.txt', os.O_RDONLY)
#os.dup2(fd, sys.stdin.fileno())

"""connected components"""

l = list(map(int, input().split()))

# node num
n = l[0]

# relation num
m = l[1]

# each node color
colors = [None] * n

rel_list = []
for _ in range(n):
    rel_list.append([])
# relation
for _ in range(m):
    l = list(map(int, input().split()))
    s = l[0]
    t = l[1]
    rel_list[s].append(t)

# coloring by DFS or BFS
for node_index in range(n):

    stack = []
    if colors[node_index] is None:
        stack.append(node_index)
        while stack:
            # process top of stack
            top = stack.pop()
            colors[top] = node_index

            relations = rel_list[top]
            for relation in relations:
                if colors[relation] is None:
                    stack.append(relation)

# question num
q = int(input())

for _ in range(q):
    l = list(map(int, input().split()))
    s = l[0]
    t = l[1]
    if colors[s] == colors[t]:
        print('yes')
    else:
        print('no')

Python: from collections import deque


def bfs(root):
    global time
    Q = deque()
    distance[root] = 0
    Q.append(root)
    i = root
    while len(Q) > 0:
        label[i] = time
        i = Q.popleft()
        for v in range(n):
            if v in adjDict[i] and color[v] == 'white':
                Q.append(v)
                color[v] = 'gray'
                distance[v] = distance[i] + 1
        color[i] = 'black'


firstline = list(map(int, input().split()))

n = firstline[0]
adjDict = {i: [] for i in range(n)}
color = ['white'] * n
distance = [-1] * n
label = [-1] * n

m = firstline[1]
for _ in range(m):
    adj = list(map(int, input().split()))
    adjDict[adj[0]].append(adj[1])

time = 0
for i in range(n):
    if color[i] == 'white':
        bfs(i)
        time += 1

q = int(input())
for i in range(q):
    question = list(map(int, input().split()))
    if label[question[0]] == label[question[1]]:
        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 i 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: def dfs(s):
    global t
    if s == t:
        return True
    DP[s]=1
    for i in F[s]:
        if not DP[i]:
            if dfs(i):
                return True
    return False
    
n,m = [int(i) for i in input().split()]
F = [{}]*n
for _ in range(m):
    i,j = [int(i) for i in input().split()]
    F[i][j] = 1
q = int(input())
for i in range(q):
    DP = [0]*n
    s,t = [int(i) for i in input().split()]
    if dfs(s):
        print("yes")
    else:
        print("no")

Python: sys.setrecursionlimit(10000)
n, m = map(int, input().split())
graph = [[] for _ in range(n)]

global visited 
visited = [0 for _ in range(n)]

def input_graph(m):
  for _ in range(m):
    u, v = map(int, input().split())
    graph[u].append(v)
    graph[v].append(u)

def dfs(node_id):
  
  for ad_node in graph[node_id]:
    if visited[ad_node] == 1:
      continue
    visited[ad_node] = 1
    dfs(ad_node)

if __name__ == "__main__":
  input_graph(m)
  q_num = int(input())
  for _ in range(q_num):
    visited = [0 for _ in range(n)]
    s, t = map(int, input().split())
    dfs(s)
    if visited[t]:
      print("yes")
    else:
      print("no")

Python: def search(s, t):
    global g
    node = g[s]
    node[1] = 1
    if s == t:
        return True
    else:
        for i in node[0]:
            ch = g[i]
            if ch[1] == 0:
                result = search(i, t)
                if result:
                    return result
        return False

n, m = list(map(int, input().split()))

g = [[[], 0] for i in range(n)]
for i in range(m):
    s, t = list(map(int, input().split()))
    g[s][0].append(t)
    g[t][0].append(s)

q = int(input())
for i in range(q):
    s, t = list(map(int, input().split()))
    result = search(s, t)
    if result:
        print("yes")
    else:
        print("no")
    for node in g:
        node[1] = 0