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: # -*- coding: utf-8 -*-
"""
Created on Sat Jul 14 10:14:13 2018
ALDS1_11_D
@author: maezawa
"""
import sys
sys.setrecursionlimit(100000)

n, m = list(map(int, input().split()))
v = [-1 for _ in range(n)]
stack = []
adj = [[] for _ in range(n)]
for i in range(m):
    s, t = list(map(int, input().split()))
    adj[s].append(t)
    adj[t].append(s)
#print(*adj, sep='\n')
def dfs(u, color):
    if v[u] > 0:
        return 0
    v[u] = color
    #print(u, current, stack)
    for k in adj[u]:
        if v[k] > 0:
            continue
        dfs(k, color)
    return 1

color = 1
for start in range(n):
    if dfs(start, color) == 1:
        color += 1
#for i in range(n):        
#    print('color:{} for node:{}'.format(i, v[i]))

q = int(input())
for i in range(q):
    s, t = list(map(int, input().split()))
    if v[s] == v[t]:
        print('yes')
    else:
        print('no')

Python: import sys
sys.setrecursionlimit(10**6)


def dfs(v, cnt):
    group[v] = cnt
    for c in edge[v]:
        if group[c] == -1:
            dfs(c, cnt)

V, E = map(int, input().split())
edge = [[] for _ in range(V)]
for _ in range(E):
    s, t = map(int, input().split())
    edge[s].append(t)
    edge[t].append(s)
group = [-1] * V
c = 0
for i in range(V):
    if group[i] == -1:
        dfs(i, c)
        c += 1

Q = int(input())
for _ in range(Q):
    s, t = map(int, input().split())
    print('yes' if group[s] == group[t] else 'no')

Python: #coding:utf-8
import sys
sys.setrecursionlimit(100000)
n, r = map(int,input().split())
Q = []
M = [[] for j in range(n)]
for i in range(r):
    i,j = map(int,input().split())
    M[i].append(j)
    M[j].append(i)


def search(person, target):
    global yes
    if yes == 1:
        return
    data = M[person]
    for per in data:
        if per ==  target:
            yes = 1
            return
        if color[per] == "white":
            color[per] = "gray"
            search(per, target)
    color[person] = "black"

num = int(input())
for i in range(num):
    yes = 0
    color = ["white" for j in range(n)]
    person, target = map(int,input().split())
    search(person, target)
    if yes == 0:
        print("no")
    else:
        print("yes")

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)
    return group_num

entry = map(int, raw_input())
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())
    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]
        affil[i] = group_num + 1
        group_num = BFS(i, group_num + 1)

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

Python: import sys
# sys.stdin = open('input.txt')

def dfs(r, c):
    S = []
    S.append(r)
    color[r] = c
    while len(S) > 0:
        u = S.pop()
        for v in G[u]:
            if color[v] is None:
                color[v] = c
                S.append(v)

def assignColors():
    colorId = 0
    for i in range(n):
        if color[i] is None:
            dfs(i, colorId)
            colorId += 1

n, m  = map(int, input().split())
G = [[] for _ in range(n)]
color = [None] * n

for i in range(m):
    s, t = map(int, input().split())
    # Doubly link
    G[s].append(t)
    G[t].append(s)

assignColors()

q = int(input())
for i in range(q):
    s, t = map(int, input().split())
    if color[s] is not None and color[s] == color[t]:
        print('yes')
    else:
        print('no')

Python: from collections import deque

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

while m:
    s, t = map(int, input().split())
    g[s].add(t)
    g[t].add(s)
    m -= 1


def find(s, t):
    global g
    queue = deque()
    queue.append((0, s))
    queue.append((1, t))
    visited = ([0] * n, [0] * n)
    visited[0][s] = 1
    visited[1][t] = 1

    def remember(visited, new):
        for i, v in enumerate(visited):
            if v:
                g[new].add(i)
                g[i].add(new)
        visited[new] = 1

    while queue:
        st, i = queue.popleft()
        for f in g[i]:
            if visited[not st][f]:
                return True
            if not visited[st][f]:
                remember(visited[st], f)
                queue.append((st, f))
    return False


q = int(input())
while q:
    s, t = map(int, input().split())
    print('yes' if find(s, t) else 'no')
    q -= 1

Python: n, m = map(int, input().split())
rootList = [-1 for i in range(n)]
 
def getRoot(x):
    if rootList[x] < 0:
        rootList[x] = x
        return x
    return getRoot(rootList[x])
 
 
def setSameRoot(x, y):
    x = getRoot(x)
    y = getRoot(y)
    if x != y:
        rootList[x], rootList[y] = min(x, y), min(x, y)
 
for i in range(m):
    s, t = map(int, input().split())
    setSameRoot(s, t)
q = int(input())
for i in range(q):
    s, t = map(int, input().split())
    print("yes" if getRoot(s) == getRoot(t) != -1 else "no")