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: def bfs(adj, s):
    n = len(adj)
    d = [-1 for _ in range(n)]
    c = [0 for _ in range(n)]

    d[s] = 0
    c[s] = 1

    queue = [s]

    while len(queue) > 0:
        u = queue.pop(0)
        for v in adj[u]:
            if c[v] == 0:
                c[v] = 1
                d[v] = d[u] + 1
                queue.append(v)

    return d


s = [int(x) for x in input().split()]
n = s[0]
m = s[1]
adj = [[] for _ in range(n)]
for _ in range(m):
    s = [int(x) for x in input().split()]
    adj[s[0]].append(s[1])
    adj[s[1]].append(s[0])

q = int(input())
for _ in range(q):
    s = [int(x) for x in input().split()]
    u = s[0]
    v = s[1]
    d = bfs(adj, u)
    if d[v] > 0:
        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 _ 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: 
NIL = -1

def assignColor():
    id = 1
    for i in range(n):
        color[i] = NIL
    for u in range(n):
        if color[u] == NIL:
            dfs(u, id)
            id += 1

def dfs(r, c):
    S = []
    S.append(r)
    color[r] = c
    while S:
        u = S.pop()
        for v in (G[u]):
            if color[v] == NIL:
                color[v] = c
                S.append(v)


nums=list(map(int,input().split()))
n = nums[0]
m = nums[1]
G = []
color = [NIL] * n

for i in range(n):
    G.append(set())
    
for i in range(m):
    nodes=list(map(int,input().split()))
    G[nodes[0]].add(nodes[1])
    G[nodes[1]].add(nodes[0])

assignColor()

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

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)

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

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

Python: def tan(G,st,fi):
    global flag
    for i in range(len(G)):
        if G[st][i] == 1:
            if i == fi:
                flag = 1
            tan(G,i,fi)
    
n,m = list(map(int, input().split()))
G = [[0 for i in range(n)] for j in range(n)]

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

q = int(input())
ans = []
for i in range(q):
    Q = list(map(int, input().split()))
    if Q[0]<Q[1]:
        st = Q[0]
        fi = Q[1]
    else:
        st = Q[1]
        fi = Q[0]

    flag = 0
    tan(G,st,fi)
    if flag==1:
        ans.append("yes")
    else:
        ans.append("no")
        
for i in range(q):
    print(ans[i])

Python: #coding:utf-8

def CC(root,dist):
    Flag=False
    if len(dist)!=0:
        for i in range(len(dist)):
            if dist[i][-1]==root[0]:
                d=dist[i]
                d=d+[root[1]]
                dist.append(d)
                Flag=True
            elif dist[i][-1]==root[1]:
                d=dist[i]
                d=d+[root[0]]
                dist.append(d)
                Flag=True
    if Flag==False:
        dist.append(root)

def Check(dist,qList):
    for i in range(len(dist)):
        if qList[0] in dist[i] and qList[1] in dist[i]:
            return "yes"
    return "no"
    
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=[]
    for i in range(m):
        CC(A[i],dist)
    q=int(input())
    for i in range(q):
        print(Check(dist,list(map(int,input().split(" ")))))