Go: package main

import (
	"fmt"
	"bufio"
	"os"
	"strconv"
)

func main() {
	var n,m int
	fmt.Scan(&n)
	group := make([]int, n)
	for i := 0; i < n; i++ {
		group[i] = i
	}
	
	fmt.Scan(&m)
	sc := bufio.NewScanner(os.Stdin)
	sc.Split(bufio.ScanWords)
	for i := 0; i < m; i++ {
		sc.Scan()
		s, _ := strconv.Atoi(sc.Text())
		sc.Scan()
		t, _ := strconv.Atoi(sc.Text())

		if group[s] < group[t] {
			group[t] = group[s]
		} else {
			group[s] = group[t]
		}
	}

	sc.Scan()
	q, _ := strconv.Atoi(sc.Text())
	for i := 0; i < q; i++ {
		sc.Scan()
		s, _ := strconv.Atoi(sc.Text())
		sc.Scan()
		t, _ := strconv.Atoi(sc.Text())

		if root(s, &group) == root(t, &group) {
			fmt.Println("yes")
		} else {
			fmt.Println("no")
		}
	}
}

func root(i int, group *[]int) int {
	if i == (*group)[i] {
		return i
	}
	(*group)[i] = root((*group)[i], group)
	return (*group)[i]
}

Python: from collections import deque

def bfs(graph, start, goal, connection):
    visited = {start: None}
    unvisited = deque()
    unvisited.append(start)
    while unvisited:
        now = unvisited.popleft()
        if now == goal or (1000000*now + goal) in connection:
            connection[1000000*start + goal] = 1
            connection[1000000*goal + start] = 1
            return "yes"
        for next in graph[now]:
            if not (next in visited):
                unvisited.append(next)
                visited[next] = now
    return "no"

n, m = map(int, input().split())
g = [[] for i in range(n)]
c = {}

for i in range(m):
    inp = list(map(int, input().split()))
    g[inp[0]].append(inp[1])
    g[inp[1]].append(inp[0])
    c[1000000*inp[0] + inp[1]] = 1
    c[1000000*inp[1] + inp[0]] = 1

q = int(input())

for i in range(q):
    s, t = map(int, input().split())
    print(bfs(g, s, t, c))

Python: import sys
sys.setrecursionlimit(100000)

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: from collections import deque

UNVISITED=0
ENTERED=1
VISITED=2

def nextNL(u, nList, state):
    l=nList[u]
    for i in l:
        if(state[i]==UNVISITED):
            return i
    return -1

def dfs(s,t,nList,state, color,icol):

    S=[]

    S.append(s)
    state[s]=ENTERED
    color[s]=icol
    while(len(S)>0):
        current=S[-1]
        next=nextNL(current, nList, state)
        if next!=-1:
            S.append(next)
            state[next]=ENTERED
            color[next]=icol
        else:
            state[S.pop()]=VISITED

    return color[s]==color[t]

def main():

    n,m=list(map(int,input().split()))
    nList=[]
    for _ in range(n):
        nList.append([])

    for _ in range(m):
        s,t=list(map(int,input().split()))
        nList[s].append(t)
        nList[t].append(s)
    
    state=[UNVISITED]*n

    q=int(input())

    icol=-1
    color=[icol]*n
    for _ in range(q):
        s,t=list(map(int,input().split()))
        if(color[s] == -1) and (color[t] == -1):
            icol+=1
            res=dfs(s,t,nList,state,color,icol)
            if(res==True):
                print('yes')
            else:
                print('no')
        elif (color[s]==-1) or (color[t]==-1):
            print('no')
        elif (color[s] == color[t]):
            print('yes')
        else:
            print('no')
    
if __name__=='__main__':
    main()

Python: n, m = [int(i) for i in input().split()]
G = [[] for _ in range(n)]
for mi in range(m):
    u, v = [int(i) for i in input().split()]
    G[u].append(v)
    G[u] += G[v]
    G[v].append(u)
    G[v] += G[u]

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

Python: from collections import deque

def bfs(graph, start, goal, connection):
    visited = {start: None}
    unvisited = deque(start)
    while unvisited:
        now = unvisited.popleft()
        if now == goal or (1000000*now + goal) in connection:
            connection[1000000*start + goal] = 1
            connection[1000000*goal + start] = 1
            return "yes"
        for next in graph[now]:
            if not (next in visited):
                unvisited.append(next)
                visited[next] = now
    return "no"

n, m = map(int, input().split())
g = [[] for i in range(n)]
c = {}

for i in range(m):
    inp = list(map(int, input().split()))
    g[inp[0]].append(inp[1])
    g[inp[1]].append(inp[0])
    c[1000000*inp[0] + inp[1]] = 1
    c[1000000*inp[1] + inp[0]] = 1

q = int(input())

for i in range(q):
    s, t = map(int, input().split())
    print(bfs(g, s, t, c))

Python: from collections import deque

def bfs(graph, start, goal, connection):
    visited = {start: None}
    unvisited = deque()
    unvisited.append(start)
    while unvisited:
        now = unvisited.popleft()
        if now == goal or goal in connection[now]:
            connection[start].add(goal)
            connection[goal].add(start)
            return "yes"
        for next in graph[now]:
            if not (next in visited):
                unvisited.append(next)
                visited[next] = now
    return "no"

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

for i in range(m):
    inp = list(map(int, input().split()))
    g[inp[0]].add(inp[1])
    g[inp[1]].add(inp[0])
    c[inp[0]].add(inp[1])
    c[inp[1]].add(inp[0])

q = int(input())

for i in range(q):
    s, t = map(int, input().split())
    print(bfs(g, s, t, c))

Python: #!/usr/bin/python3
n, m = map(int, input().split())
ALL = [0] * n
Graph = []
for i in range(m):
    s, t = map(int, input().split())
    if ALL[s] == 0 and ALL[t] == 0:
        Graph.append(set([s, t]))
    elif ALL[s] == 0:
        for g in Graph:
            if t in g:
                g.add(s)
                break
    elif ALL[t] == 0:
        for g in Graph:
            if s in g:
                g.add(t)
                break
    ALL[s] = 1
    ALL[t] = 1

q = int(input())
for i in range(q):
    s, t = map(int, input().split())
    for g in Graph:
        if s in g and t in g:
            print('yes')
            break
    else:
        print('no')

Python: import sys

sys.setrecursionlimit(1000000)

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
    visited = [0] * n

    def dfs(i):
        visited[i] = 1
        if i == t:
            return True
        for f in g[i]:
            if not visited[f]:
                if dfs(f):
                    return True
        return False

    return dfs(s)


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