Go: package main

import (
	"bufio"
	"container/list"
	"fmt"
	"os"
	"strconv"
)

//util
var sc = bufio.NewScanner(os.Stdin)

func nextStr() string {
	sc.Scan()
	return sc.Text()
}

func nextInt() int {
	sc.Scan()
	i, e := strconv.Atoi(sc.Text())
	if e != nil {
		panic(e)
	}
	return i
}

func printList(list []int) {
	n := len(list)
	buf := bufio.NewWriter(os.Stdout)
	for _, v := range list[0 : n-1] {
		buf.Write([]byte(fmt.Sprintf("%d ", v)))
	}
	buf.Write([]byte(fmt.Sprintf("%d\n", list[n-1])))
	buf.Flush()
}

func max(a, b int) int {
	if a > b {
		return a
	} else {
		return b
	}
}

func min(a, b int) int {
	if a > b {
		return b
	} else {
		return a
	}
}

//solve
const (
	MAX = 100000
	NIL = -1
)

var (
	n, m, q, s, t int
	G             [MAX][]int //連結リスト
	color         [MAX]int
)

func dfs(r int, c int) {
	S := list.New()
	S.PushFront(r)
	color[r] = c
	for S.Len() != 0 {
		u := S.Remove(S.Front()).(int)
		for i := 0; i < len(G[u]); i++ {
			v := G[u][i]
			if color[v] == NIL {
				color[v] = c
				S.PushFront(v)
			}
		}
	}
}

//幅優先探索で、頂点を色付け
func assignColor() {
	id := 1
	for i := 0; i < n; i++ {
		color[i] = NIL
	}
	for i := 0; i < n; i++ {
		if color[i] == NIL {
			id++
			dfs(i, id)
		}
	}
}

func main() {
	sc.Split(bufio.ScanWords)
	n, m = nextInt(), nextInt()
	for i := 0; i < m; i++ {
		s, t = nextInt(), nextInt()
		if i == 0 {
			G[s] = make([]int, 0)
			G[t] = make([]int, 0)
		}
		G[s] = append(G[s], t)
		G[t] = append(G[t], s)

	}
	assignColor()
	q = nextInt()
	for i := 0; i < q; i++ {
		s, t = nextInt(), nextInt()
		if color[s] == color[t] {
			fmt.Println("yes")
		} else {
			fmt.Println("no")
		}
	}

}

Python: import sys
input_lines = [[int(i) for i in line.split()] for line in sys.stdin.read().splitlines()]
[user_num, rel_num] = input_lines[0]
rel_list = input_lines[1:rel_num+1]
ques_num = input_lines[rel_num+1][0]
ques_list = input_lines[rel_num+2:]
color_list = [-1] * user_num
adja_list = [set() for i in range(user_num)]

def dfs(id, color):
    if color_list[id] == -1:
        color_list[id] = color
        for a_id in adja_list[id]:
            dfs(a_id, color)



for rel in rel_list:
    adja_list[rel[0]].add(rel[1])
    adja_list[rel[1]].add(rel[0])

color = 0
for id in range(user_num):
    print(color_list)
    dfs(id, color)
    color += 1

for ques in ques_list:
    if color_list[ques[0]] == color_list[ques[1]]:
        print('yes')
    else:
        print('no')

Python: n, m = map(int, input().split())

a = [[] for i in range(n)]

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

q = int(input())

from collections import deque



for j in range(q):
    queue = deque()
    memo = [0 for i in range(n)]
    data = list(map(int, input().split()))
    memo[data[0]] = 1
    queue.append(data[0])

    try:
        while len(queue) != 0:
            b = queue.popleft()
            if len(a[b]) != 0:
                for k in a[b]:
                    if memo[k] == 0:
                        memo[k] = 1
                        queue.append(k)
                        if k == data[1]:
                            print("yes")
                            raise Exception
        print("no")
    except Exception:
        pass

Python: n,m=map(int,input().split())
P=[[]for _ in[0]*n]
C=[0]*n
k=0
for _ in[0]*m:
 s,t=map(int,input().split());P[s]+=[t];P[t]+=[s]
for i in range(n):
 k+=1
 if C[i]<1:
  s=[i];C[i]=k
  while s:
   u=s.pop()
   for v in P[u]:
    if C[v]<1:C[v]=k;s+=[v]
for _ in[0]*int(input()):
 a,b=map(int,input().split())
 print(['no','yes'][C[a]==C[b]])

Python: def dfs(r, c):
    global color, G
    S = [r]
    color[r] = c
    while (0 < len(S)):
        u = S.pop()
        for u in G[u]:
            v = color[u]
            if (v == None):
                color[u] = c
                S.append(u)
 
def assignColor():
    global color, G, n
    c = 1
    for i in range(n):
        if (color[i] == None):
            dfs(i, c)
            c += 1
 
n, m = list(map(int, input().split()))
 
G = [[] for i in range(n)]
for i in range(m):
    s, t = list(map(int, input().split()))
    G[s].append(t)
    G[t].append(s)
 
color = [None for i in range(n)]
 
assignColor()
 
q = int(input())

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

Python: import sys
from collections import deque

def debug(x, table):
    for name, val in table.items():
        if x is val:
            print('DEBUG:{} -> {}'.format(name, val), file=sys.stderr)
            return None

def paint_col(adj, cols, i, col):
    nxt = deque([i])

    while nxt:
        u = nxt.popleft()
        cols[u] = col
        for child in adj[u]:
            if cols[child] == 0:
                nxt.append(child)

def solve():
    n, m = map(int, sys.stdin.readline().split())
    adj = [[] for i in range(n)]

    for i in range(m):
        s, t = map(int, sys.stdin.readline().split())
        adj[s].append(t)
        adj[t].append(s)

    cols = [0] * n
    col = 1

    for i in range(n):
        if cols[i] == 0:
            paint_col(adj, cols, i, col)
            col += 1

    q = int(sys.stdin.readline())

    for i in range(q):
        s, t = map(int, sys.stdin.readline().split())

        if cols[s] == cols[t]:
            ans = 'yes'
        else:
            ans = 'no'

        print(ans)

if __name__ == '__main__':
    solve()

Python: n, m = map(int, input().split())

adj = [[] for _ in range(n)] # adjacent list

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

c = ['w']*n # color of each vertex
con = [0]*n
cnt = 0

   
def DFS_visit(u):
    global c 
    global con
    global cnt
    c[u] = 'g'
    con[u] = cnt
    for v in adj[u]:
        if c[v] == 'w':
            DFS_visit(v)
    c[u] = 'b'
        
for u in range(n):
    if c[u] == 'w':
        cnt += 1
        DFS_visit(u)
        
        
q = int(input())
for _ in range(q):
    u, v = map(int, input().split())
    ans = "yes" if (con[u] == con[v]) else "no"
    print(ans)

Python: #!/usr/bin/python3

def set_color(i, ci, e, color):
    color[i] = ci
    next_i = set(e[i])
    while len(next_i):
        s = next_i.pop()
        if color[s] != ci:
            color[s] = ci
            next_i.update(e[s])


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

e = [set() for i in range(n)]
color = [None] * n

for i in range(m):
    s, t = map(int, input().split())
    e[s].add(t)
    e[t].add(s)

ci = 0
for i in range(n):
    if color[i] == None:
        set_color(i, ci, e, color)
        ci += 1

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

Python: import queue

N, M = map(int, input().split())
G = [[] for _ in range(N)]
for _ in range(M):
    s, t = map(int, input().split())
    G[s].append(t)
    G[t].append(s)

group = [0] * N
group_id = 1
que = queue.Queue()

for i in range(N):
    if group[i] != 0:
        continue
    group[i] = group_id
    que.put(G[i])
    while not que.empty():
        q = que.get()
        for j in q:
            if group[j] == 0:
                que.put(G[j])
                group[j] = group_id
    group_id += 1

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