Go: package main

import (
	"fmt"
)

var n, m int
var g [][]int
var color []int

func main() {
	fmt.Scan(&n, &m)
	g = make([][]int, n) // SNSの関係を表すグラフ
	for i := 0; i < m; i++ {
		var a, b int
		fmt.Scan(&a, &b)
		g[a] = append(g[a], b) // 無向重みなしグラフ
		g[b] = append(g[b], a)
	}
	color = make([]int, n) // 各ノードにつける色
	for i := 0; i < len(color); i++ {
		color[i] = -1 // 初期化しておく
	}
	type query struct {
		s, t int
	}
	var Q int
	fmt.Scan(&Q)
	qs := make([]query, Q)
	for i := 0; i < Q; i++ {
		fmt.Scan(&qs[i].s, &qs[i].t)
	}
	// fmt.Println("n", n, "m", m, "g", g, "Q", Q, "qs", qs)
	// 全ての頂点からdfsする
	id := 1
	for u := 0; u < n; u++ {
		if color[u] == -1 {
			dfs(u, id)
			id++
		}
	}
	// fmt.Println("color", color)
	for i := 0; i < Q; i++ {
		if color[qs[i].s] == color[qs[i].t] {
			fmt.Println("yes")
		} else {
			fmt.Println("no")
		}
	}
}

func dfs(v, c int) {
	// fmt.Printf("dfs(v %d, c %d) en:\n", v, c)
	color[v] = c
	for _, vv := range g[v] {
		// fmt.Printf("  v %d, g[v] %v, vv %d\n", v, g[v], vv)
		if color[vv] == -1 {
			dfs(vv, c)
		}
	}
}

Python: from collections import defaultdict


n, m = map(int, input().split())
rel = defaultdict(set)

for _ in range(m):
    p, r = map(int, input().split())
    rel[p].add(r)
    rel[r].add(p)


color = defaultdict(int)

def search(f, c):
    stack = [f]
    color[f] = c
    while stack:
        u = stack.pop()
        for v in rel[u]:
            if not color[v]:
                color[v] = c
                stack.append(v)


# assign color
cl = 0
for i in range(n):
    if not color[i]:
        cl += 1
        search(i, cl)

qn = int(input())

for _ in range(qn):
    f, l = map(int, input().split())
    print(['no', 'yes'][color[f] == color[l]])

Python: import sys
sys.setrecursionlimit(200000)

def dfs(v):
    global node_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
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])

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: n = list(map(int,input().split()))
cn = [i for i in range(n[0])]
cnt = [[0]]*n[0]
for i in range(1,n[0]):
    cnt[i] = [i]
x = [1]*n[0]

for i in range(n[1]):
    a = list(map(int,input().split()))
    if cn[a[0]] != cn[a[1]]:
        if x[a[0]] > x[a[1]]: 
            tmp = cn[a[1]]
            tmp2 = cn[a[0]]
        else: 
            tmp = cn[a[0]]
            tmp2 = cn[a[1]]
        for j in cnt[tmp]:
            cn[j] = cn[tmp2]
        x[tmp2] += len(cnt[tmp])
        cnt[tmp2].extend(cnt[tmp])
        cnt[tmp] = [-1]

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

Python: # -*- coding: utf-8 -*-

def assignColor(G):
    n = len(G)
    C = [-1 for i in range(n)]
    for i in range(n):
        if C[i] == -1:
            C = BFS(G, i, C)
    return C

#@profile
def BFS(G, start, C):
    n = len(G)
    Q = [start]
    C[start] = start

    while len(Q) != 0:
        u = Q.pop(0)
        v = [i for i in G[u] if C[i] == -1] # v := ??£??\???????????????????????¢?´¢??????????????????
        
        for i in v:
            Q.append(i)
            C[i] = C[start]
    
    return C

def main():
    
    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)

    C = assignColor(G)
        
    q = int(input())
    
    for i in range(q):
        s, t = list(map(int, input().split()))
        if C[s] == C[t]:
            print("yes")
        else:
            print("no")
            
if __name__ == "__main__":
    main()

Python: import sys
sys.setrecursionlimit(1000000)

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

for _ in range(m):
    a,b=map(int,input().split())
    graph[a].append(b)
    graph[b].append(a)

def dfs(v):
    if reached[v]:
        reached[v]=0
        ll.add(v)
        for i in range(len(graph[v])):
            dfs(graph[v][i])

reached=[1]*n
ans=[[] for _ in range(n)]

for j in range(n):
    ll=set()
    dfs(j)
    if ll:
        for s in ll:
            ans[s]=ll

q=int(input())
ab=[]
for i in range(q):
    a,b=map(int,input().split())
    ab.append([a,b])

for i in range(q):
    a,b=ab[i][0],ab[i][1]
    if b in ans[a]:
        print("yes")
    else:
        print("no")

Python: def s():
 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]])
if'__main__'==__name__:s()

Python: from collections import deque
from enum import Enum, auto
import sys
sys.setrecursionlimit(100000)

class Color(Enum):
    WHITE = auto()
    GRAY = auto()
    BLACK = auto()

n, m = list(map(int, input().split(' ')))
adj_list = [[] for i in range(n)]
for i in range(m):
    u, v = list(map(int, input().split(' ')))
    adj_list[u].append(v)
    adj_list[v].append(u)

# 幅優先
def adj_bfs(s, e):
    queue = deque([])
    colors = [Color.WHITE for i in range(n)]

    queue.append(s)
    colors[s] = Color.GRAY

    while len(queue) > 0:
        u = queue.popleft()
        for v in adj_list[u]:
            if colors[v] == Color.WHITE:
                colors[v] = Color.GRAY
                queue.append(v)
                if v == e: return True
        colors[u] = Color.BLACK
    return False

# 深さ優先
colors = [Color.WHITE for i in range(n)]

def adj_dfs(u, e):
    colors[u] = Color.GRAY

    for v in adj_list[u]:
        if colors[v] == Color.WHITE:
            if v == e: return True
            if adj_dfs(v, e):
                return True

    colors[u] = Color.BLACK
    return False

q = int(input())
for i in range(q):
    s, e = list(map(int, input().split(' ')))
    colors = [Color.WHITE for i in range(n)]
    if adj_dfs(s, e):
        print('yes')
    else:
        print('no')

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 = [False 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: n, m = map(int, input().split())
rootList = [-1 for i in range(n)]
 
def getRoot(x):
    r = rootList[x]
    if r < 0:
        rootList[x] = x
    elif r != x:
        rootList[x] = getRoot(r)
    return rootList[x]
 
 
def setSameRoot(x, y):
    x = getRoot(x)
    y = getRoot(y)
    if x != y:
        rootList[x] = rootList[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) else "no")