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: # ALDS1_11_D Connected Components
import sys
import queue


sys.setrecursionlimit(1000000)

def check(adj, foot_print):
    n = len(foot_print)
    que = queue.Queue()
    num = 0
    for i in range(n):
        if foot_print[i] == 0:
            num += 1
            que.put(i)
            foot_print[i] = num
            bfs(adj, que, foot_print, num)


def bfs(adj, que, foot_print, num):
    if not que.empty():
        now = que.get()
        for i in adj[now]:
            if foot_print[i] == 0:
                foot_print[i] = num
                que.put(i)
        bfs(adj, que, foot_print, num)
    else:
        return


def main():
    n, m = map(int, sys.stdin.readline().strip().split())
    adj_list = [[] for _ in range(n)]
    for i in range(m):
        s, t = map(int, sys.stdin.readline().strip().split())
        adj_list[s].append(t)
        adj_list[t].append(s)

    foot_print = [0] * n
    check(adj_list, foot_print)

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


if __name__ == '__main__':
    main()

Python: n, m = map(int, input().split())
rootList = [-1] * n

def getRoot(x):
    if rootList[x] < 0:
        return x
    return getRoot(rootList[x])


def setSameRoot(x, y):
    x = getRoot(x)
    y = getRoot(y)
    if x != y:
        G[x], G[y] = min(x, 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")

Python: #!/usr/bin/env python
# -*- coding: utf-8 -*-
 
import sys
 
 
def assign_color():
    _color = 1
    for m in range(vertices_num):
        if vertices_status_list[m] == -1:
            graph_dfs(m, _color)
            _color += 1
    return None
 
 
def graph_dfs(vertex, color):
    vertices_stack = list()
    vertices_stack.append(vertex)
    vertices_status_list[vertex] = color
 
    while vertices_stack:
        current_vertex = vertices_stack[-1]
        vertices_stack.pop()
        for v in adj_list[current_vertex]:
            if vertices_status_list[v] == -1:
                vertices_status_list[v] = color
                vertices_stack.append(v)
    return None
 
 
def solve():
    for relation in relation_info:
        key, value = map(int, relation.split())
        adj_list[key].append(value)
        adj_list[value].append(key)
 
    assign_color()
 
    # print(adj_list)
    for question in question_list:
        start, target = map(int, question.split())
        if vertices_status_list[start] == vertices_status_list[target]:
            print("yes")
        else:
            print("no")
    return vertices_status_list
 
 
if __name__ == '__main__':
    _input = sys.stdin.readlines()
    vertices_num, relation_num = map(int, _input[0].split())
 
    relation_info = _input[1:relation_num + 1]
 
    question_num = int(_input[relation_num + 1])
    question_list = _input[relation_num + 2:]
 
    adj_list = tuple([[] for _ in range(vertices_num)])
    vertices_status_list = [-1] * vertices_num
    ans = solve()

Python: def connect(o,s,t):
    global ct
    if color[s]!="white" or ct!=1:
        return
    if fr[o][t]==t:
        ct+=1
    color[s]="grey"
    for i in fr[s]:
        if i==-1:
            continue
        elif i==t or ct!=0:
             ct+=1
             break
        else:
            fr[o][i]=i
            fr[i][o]=s
            connect(o,i,t)
            
n,m=map(int,raw_input().split())
fr=[[-1]*n for i in xrange(n)]
for i in xrange(m):
    s,t=map(int,raw_input().split())
    fr[s][t]=t
    fr[t][s]=s
q=input()
for i in xrange(q):
    ct=0
    color=["white"]*n
    s,t=map(int,raw_input().split())
    connect(s,s,t)
    if ct==0:
        print('no')
    else:
        print('yes')
        fr[s][t]=t
        fr[t][s]=s

Python: #!/usr/bin/env python
# -*- coding: utf-8 -*-

import sys


def assign_color():
    _color = 1
    for m in range(vertices_num):
        if vertices_status_list[m] == -1:
            graph_dfs(m, _color)
            _color += 1
    return None


def graph_dfs(vertex, color):
    vertices_stack = list()
    vertices_stack.append(vertex)
    vertices_status_list[vertex] = color
    while vertices_stack:
        current_vertex = vertices_stack[-1]
        vertices_stack.pop()
        for v in adj_list[current_vertex]:
            if vertices_status_list[v] == -1:
                vertices_status_list[v] = color
                vertices_stack.append(v)
    return None


if __name__ == '__main__':
    _input = sys.stdin.readlines()
    vertices_num, relation_num = map(int, _input[0].split())

    relation_info = _input[1:relation_num + 1]

    question_num = int(_input[relation_num + 1])
    question_list = _input[relation_num + 2:]

    adj_list = [[] for _ in range(vertices_num)]
    vertices_status_list = [-1] * vertices_num

    for relation in relation_info:
        key, value = map(int, relation.split())
        adj_list[key].append(value)
        adj_list[value].append(key)

    assign_color()

    # print(adj_list)
    for question in question_list:
        start, target = map(int, question.split())
        if vertices_status_list[start] == vertices_status_list[target]:
            print("yes")
        else:
            print("no")