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: from collections import deque


def bfs(adj_list, n):
    color = [None] * n
    color_count = 0
    searching = deque()
    for i in range(n):
        if color[i] is None:
            color_count += 1
            color[i] = color_count
            searching.append(i)
            while len(searching) > 0:
                start = searching.popleft()
                for end in adj_list[start]:
                    if color[end] is None:
                        color[end] = color_count
                        searching.append(end)
    return color


def dfs(adj_list, n):
    color = [None] * n
    color_count = 0
    searching = deque()
    for i in range(n):
        if color[i] is None:
            color_count += 1
            color[i] = color_count
            searching.append(i)
            while len(searching) > 0:
                start = searching.pop()
                for end in adj_list[start]:
                    if color[end] is None:
                        color[end] = color_count
                        searching.append(end)
    return color


def main():
    nm = input().split()
    n, m = list(map(int, nm))
    adj_list = [[] for _ in range(n)]
    for _ in range(m):
        st = input().split()
        s, t = list(map(int, st))
        adj_list[s].append(t)
        adj_list[t].append(s)
    color = dfs(adj_list, n)
    q = int(input())
    for _ in range(q):
        st = input().split()
        s, t = list(map(int, st))
        if color[s] == color[t]:
            print("yes")
        else:
            print("no")


if __name__ == "__main__":
    main()

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 = (set(), set())
    visited[0].add(s)
    visited[1].add(t)

    def remember(visited, new):
        g[new] |= visited
        for v in visited:
            g[v].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: #coding:utf-8

def CC(root,dist):
    for i in range(len(dist)):
        if i==root[0]:
            dist[i]=dist[i]+[root[1]]
        elif i==root[1]:
            dist[i]=dist[i]+[root[0]]
        
def Check(dist,start,end,clist):
    ans="no"
    if len(dist[end])!=0:
        if start in dist[end]:
            ans="yes"
        else:
            clist.append(end)
            for d in dist[end]:
                if d!=end and d not in clist:
                    ans=Check(dist,start,d,clist)
                    if ans=="yes":
                        break
    return ans
    
if __name__=="__main__":
    I=input()
    n=int(I.split(" ")[0])
    m=int(I.split(" ")[1])
    A=[]
    for i in range(m):
        A.append(list(map(int,input().split(" "))))
    dist=[[]]*n
    for i in range(m):
        CC(A[i],dist)
    q=int(input())
    for i in range(q):
        qList=list(map(int,input().split(" ")))
        print(Check(dist,qList[0],qList[1],[]))

Python: 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


if __name__ == "__main__":
    n, m = map(int, sys.stdin.readline().split())
    setlist = []
    inp = sys.stdin.readlines()
    for i in range(m):
        inp_i = list(map(int, inp[i].split()))
        for j in range(len(setlist)):
            if inp_i[0] in setlist[j] or inp_i[1] in setlist[j]:
                setlist[j].add(inp_i[0])
                setlist[j].add(inp_i[1])
                break
            if j == len(setlist)-1:
                setlist.append(set([inp_i[0], inp_i[1]]))
        if i == 0:
            setlist.append(set([inp_i[0], inp_i[1]]))
    for i in range(int(inp[m])):
        inp_i = list(map(int, inp[i+m+1].split()))
        for j in range(len(setlist)):
            if inp_i[0] in setlist[j]:
                if inp_i[1] in setlist[j]:
                    print("yes")
                    break
                else:
                    print("no")
                    break