Problem:


  MathJax.Hub.Config({ tex2jax: { inlineMath: [["$","$"], ["\\(","\\)"]], processEscapes: true }});

Connected Components

  Write a program which reads relations in a SNS (Social Network Service), and judges that given pairs of users are reachable each other through the network.

Input

  In the first line, two integer $n$ and $m$ are given. $n$ is the number of users in the SNS and $m$ is the number of relations in the SNS. The users in the SNS are identified by IDs $0, 1, ..., n-1$.

  In the following $m$ lines, the relations are given. Each relation is given by two integers $s$ and $t$ that represents $s$ and $t$ are friends (and reachable each other).

  In the next line, the number of queries $q$ is given. In the following $q$ lines, $q$ queries are given respectively. Each query consists of two integers $s$ and $t$ separated by a space character.

Output

  For each query, print "yes" if $t$ is reachable from $s$ through the social network, "no" otherwise.

Constraints

$2 \leq n \leq 100,000$

$0 \leq m \leq 100,000$

$1 \leq q \leq 10,000$

Sample Input

10 9
0 1
0 2
3 4
5 7
5 6
6 7
6 8
7 8
8 9
3
0 1
5 9
1 3

Sample Output

yes
yes
no



Sample input:
10 9
0 1
0 2
3 4
5 7
5 6
6 7
6 8
7 8
8 9
3
0 1
5 9
1 3


Sample output:
yes
yes
no

Submission status: Accepted

Solution code:
# -*- coding: utf-8 -*-
"""
Created on Sat Apr  6 14:09:17 2019

@author: Yamazaki Kenichi
"""
import sys
sys.setrecursionlimit(10**6)

n,m = map(int,input().split())
A = [list(map(int,input().split())) for i in range(m)]
q = int(input())
Q = [list(map(int,input().split())) for i in range(q)]

class UnionFind(object):
    def __init__(self,size):
        self.table = [-1 for i in range(size)]
    def find(self,x):
        if self.table[x] < 0:
            return x
        else:
            self.table[x] = self.find(self.table[x])
            return self.table[x]
    def union(self,x,y):
        s1 = self.find(x)
        s2 = self.find(y)
        if s1 != s2:
            if self.table[s1] <= self.table[s2]:
                self.table[s1] += self.table[s2]
                self.table[s2] = s1
            else:
                self.table[s2] += self.table[s1]
                self.table[s1] = s2
            return True
        else:
            return False
    def check(self,x,y):
        s1 = self.find(x)
        s2 = self.find(y)
        if s1 != s2:
            return False
        else:
            return True

uf = UnionFind(n)
for c in A:
    uf.union(c[0],c[1])
for c in Q:
    if uf.check(c[0],c[1]):
        print('yes')
    else:
        print('no')

Submission status: Accepted

Solution code:
n, m = map(int, input().split())
g = [[] for _ in range(n)]
for i in range(m):
    s, t = map(int, input().split())
    g[s].append(t)
    g[t].append(s)

# dfsで連結成分を求める
r = [0]*n
for i in range(n):
    if r[i] == 0:
        l = [i]
        while len(l) > 0:
            u = l.pop(-1)
            r[u] = i+1
            for v in g[u]:
                if r[v] == 0:
                    l.append(v)

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

Submission status: Accepted

Solution code:
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]])

Submission status: Accepted

Solution code:
V,E = map(int,input().split())
 
boss = [i for i in range(V)]
height = [0 for i in range(V)]
 
def get_boss(index):
    if index == boss[index]:
        return index
    else:
        boss[index] = get_boss(boss[index])
        return boss[index]
 
 
def is_same_group(a,b):
    return get_boss(a) == get_boss(b)
 
def unite(x,y):
    boss_x = get_boss(x)
    boss_y = get_boss(y)
 
    if boss_x == boss_y:
        return
 
    if height[x] > height[y]:
 
        boss[boss_y] = boss_x
 
    elif height[x] < height[y]:
 
        boss[boss_x] = boss_y
 
    else:
        boss[boss_y] = boss_x
        height[x] += 1
 
 
for loop in range(E):
    A,B = map(int,input().split())
    unite(A,B)
 
num_query = int(input())
 
for loop in range(num_query):
    A,B = map(int,input().split())
    if is_same_group(A,B) == True:
        print("yes")
    else:
        print("no")

Submission status: Accepted

Solution code:
import sys
from collections import defaultdict

def main():
    lines = sys.stdin.readlines()
    n, m = map(int, lines[0].split())
    relation_lines = lines[1:1+m]

    relations = defaultdict(list)

    for idx, relation_line in enumerate(relation_lines):
        s, t = relation_line.split()
        relations[s].append(t)
        relations[t].append(s)

    group = {}
    for key in relations.keys():
        group[key] = -1
    group_num = 0

    # assign a group number for ids
    for key, val in relations.items():
        if group[key] != -1:
            continue

        group[key] = group_num
        group_num += 1

        group_no = group[key]
        friends = [key]

        while len(friends) != 0:
            n_fs = relations[friends.pop()]
            for n_f in n_fs:
                if group[n_f] == -1:
                    group[n_f] = group_no
                    friends.append(n_f)

    q = int(lines[1+m])
    question_lines = lines[1+m+1:]
    answers = [None] * q
    for i, question in enumerate(question_lines):
        s, t = question.split()

        if s not in group or t not in group:
            answers[i] = 'no'
            continue
        elif group[s] == group[t]:
            answers[i] = 'yes'
        else:
            answers[i] = 'no'

    # answer
    [print(ans) for ans in answers]
    return

main()

Submission status: Accepted

Solution code:
import sys
readline = sys.stdin.readline
write = sys.stdout.write
N, M = map(int, readline().split())
*p, = range(N)
def root(x):
    if x == p[x]:
        return x
    p[x] = x = root(p[x])
    return x
def unite(x, y):
    px = root(x); py = root(y)
    if px < py:
        p[py] = px
    else:
        p[px] = py


for i in range(M):
    s, t = map(int, readline().split())
    unite(s, t)
*_, = map(root, range(N))
Q = int(readline())
ans = []
for q in range(Q):
    s, t = map(int, readline().split())
    ans.append('yes' if p[s] == p[t] else 'no')
write("\n".join(ans))
write("\n")

Submission status: Accepted

Solution code:
def read_friends():
    n, m = [int(x) for x in input().split()]
    adj_list = [set() for _ in range(n)]

    for _ in range(m):
        s, t = [int(x) for x in input().split()]
        adj_list[s].add(t)
        adj_list[t].add(s)

    return n, adj_list


def divide_group(n, adj_list):
    group = [None] * n

    def visit(k, g):
        S = [k]

        while S:
            k = S.pop()
            group[k] = g
            for t in adj_list[k]:
                if group[t] is None:
                    S.append(t)

    for k in range(n):
        if group[k] is None:
            visit(k, k)

    return group


def answer_queries(group):
    q = int(input())

    for _ in range(q):
        s, t = [int(x) for x in input().split()]
        print("yes" if group[s] == group[t] else "no")


def main():
    n, adj_list = read_friends()
    group = divide_group(n, adj_list)
    answer_queries(group)


if __name__ == '__main__':
    main()

Submission status: Accepted

Solution code:
v, e = map(int, input().split())   #ユーザ数、関係性の数
edge = [[] for _ in range(v)]      #お隣さんリスト


#連結成分作成部分のコード（各頂点を一度ずつ訪問して隣接リスト内の辺を訪問）
for _ in range(e):                 #関係性の数だけ
  s, t = map(int, input().split()) #始点と終点を入れる
  edge[s].append(t)                #sのお隣さんリストにtを
  edge[t].append(s)                #tのお隣さんリストにsを

group = [-1]*v                     #グループというリストを作る（こいつの値であとで友達か照合）
cnt = 0                            #グループ番号


#隣接リストに入っている同じエッジをスタックに入れてグループ化する
for i in range(v):
  if group[i] == -1:
    group[i] = cnt                 #カウントの値を入れる
    stack = [i]                    #エッジ番号を入れる
    while stack:
      v = stack.pop()              #エッジを代入　ー①
      for c in edge[v]:            #①のエッジのお隣さんリストを辿っていく
        if group[c] == -1:         #お隣さんのグループが初期化状態なら
          group[c] = cnt          #グループリストにカウントを入れる
          stack.append(c)          #スタックにお隣さんを入れる
    cnt += 1                       #お隣さんの訪問が終わったらグループ番号を変える

#クエリのコード
for _ in range(int(input())):
  s, t = map(int, input().split())
  print('yes' if group[s] == group[t] else 'no')

Submission status: Accepted

Solution code:
from enum import Enum
import sys
import math

BIG_NUM = 2000000000
MOD = 1000000007
EPS = 0.000000001


V,E = map(int,input().split())

boss = [i for i in range(V)]
height = [0 for i in range(V)]

def get_boss(index):
    if index == boss[index]:
        return index
    else:
        boss[index] = get_boss(boss[index])
        return boss[index]


def is_same_group(a,b):
    return get_boss(a) == get_boss(b)

def unite(x,y):
    boss_x = get_boss(x)
    boss_y = get_boss(y)

    if boss_x == boss_y:
        return

    if height[x] > height[y]:

        boss[boss_y] = boss_x

    elif height[x] < height[y]:

        boss[boss_x] = boss_y

    else:
        boss[boss_y] = boss_x
        height[x] += 1


for loop in range(E):
    A,B = map(int,input().split())
    unite(A,B)

num_query = int(input())

for loop in range(num_query):
    A,B = map(int,input().split())
    if is_same_group(A,B) == True:
        print("yes")
    else:
        print("no")

Submission status: Accepted

Solution code:
class Vertex:
	def __init__(self):
		self.c = 0
		self.vertices = []
	def add(self, u):
		self.vertices.append(u)

def dfs(vertices):
	c = 0
	for i in range(len(vertices)):
		c += 1
		if vertices[i].c == 0:
			vertices[i].c = c
			stack = []
			stack.append(i)
			while len(stack) != 0:
				cur = vertices[stack.pop()]
				for j in range(len(cur.vertices)):
					u = cur.vertices[j]
					if vertices[u].c == 0:
						vertices[u].c = c
						stack.append(u)
	return

n, m = map(int, input().split())
vertices = []
for i in range(n):
	vertices.append(Vertex())
for i in range(m):
	u1, u2 = map(int, input().split())
	vertices[u1].add(u2)
	vertices[u2].add(u1)

dfs(vertices)

q = int(input())
for i in range(q):
	u1, u2 = map(int, input().split())
	if vertices[u1].c == vertices[u2].c:
		print('yes')
	else:
		print('no')

Submission status: Accepted

Solution code:
def dfs(r, c, g, color):
    s = [r]
    color[r] = c
    while len(s) != 0:
        u = s.pop()
        for i in range(len(g[u])):
            v = g[u][i]
            if color[v] is None:
                color[v] = c
                s.append(v)


def assignColor(n, g, color):
    color_id = 1
    for u in range(n):
        if color[u] is None:
            dfs(u, color_id, g, color)
            color_id += 1


n, m = [int(v) for v in input().split()]
g = [[] for i in range(n)]
for i in range(m):
    s, t = [int(v) for v in input().split()]
    g[s].append(t)
    g[t].append(s)

color = [None] * n
assignColor(n, g, color)

q = int(input())

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

Submission status: Accepted

Solution code:
n, m = map(int, input().split())
relations = [[] for _ in range(n)]
 
for i in range(m):
    s, t = map(int, input().split())
    relations[s] += [t]
    relations[t] += [s]
friend_id = [None] * n
for s, t in enumerate(relations):
    if t:
        queue = [s]
        while len(queue):
            k = queue.pop()
            friend_id[k] = s
            queue += relations[k]
            relations[k] = []
 
q = int(input())
for i in range(q):
    s, t = map(int, input().split())
    print('yes' if friend_id[s] != None and friend_id[s] == friend_id[t] else'no')

Submission status: Accepted

Solution code:
# Graph I - Connected Components
import array
from collections import deque
def groupify(length, adj_list):
    group = array.array('l', (-1 for _ in range(length)))
    g_id = 0
    dq = deque()
    for idx in range(length):
        if group[idx] == -1:
            group[idx] = g_id
            dq.append(idx)
            while len(dq):
                v = dq.popleft()
                for t in adj_list[v]:
                    if group[t] == -1:
                        group[t] = g_id
                        dq.append(t)
            g_id += 1
    return group

n,m = map(int, input().split())
adj_list = [set() for _ in range(n)]
for _ in range(m):
    i,j = map(int, input().split())
    adj_list[i].add(j)
    adj_list[j].add(i)
group = groupify(n, adj_list)

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

Submission status: Runtime Error

Solution code:
# -*- coding: utf-8 -*-
"""
Created on Sat Jul 14 10:14:13 2018
ALDS1_11_D
@author: maezawa
"""

n, m = list(map(int, input().split()))
v = [-1 for _ in range(n)]
stack = []
adj = [[] for _ in range(n)]
for i in range(m):
    s, t = list(map(int, input().split()))
    adj[s].append(t)
    adj[t].append(s)
#print(*adj, sep='\n')
def dfs(u, color):
    if v[u] > 0:
        return 0
    v[u] = color
    #print(u, current, stack)
    for k in adj[u]:
        if v[k] > 0:
            continue
        dfs(k, color)
    return 1

color = 1
for start in range(n):
    if dfs(start, color) == 1:
        color += 1
#for i in range(n):        
#    print('color:{} for node:{}'.format(i, v[i]))

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

Submission status: Runtime Error

Solution code:
# -*- coding: utf-8 -*-
"""
Created on Sat Jul 14 10:14:13 2018
ALDS1_11_D
@author: maezawa
"""
import sys
sys.setrecursionlimit(10000)

n, m = list(map(int, input().split()))
v = [-1 for _ in range(n)]
stack = []
adj = [[] for _ in range(n)]
for i in range(m):
    s, t = list(map(int, input().split()))
    adj[s].append(t)
    adj[t].append(s)
#print(*adj, sep='\n')
def dfs(u, color):
    if v[u] > 0:
        return 0
    v[u] = color
    #print(u, current, stack)
    for k in adj[u]:
        if v[k] > 0:
            continue
        dfs(k, color)
    return 1

color = 1
for start in range(n):
    if dfs(start, color) == 1:
        color += 1
#for i in range(n):        
#    print('color:{} for node:{}'.format(i, v[i]))

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

Submission status: Runtime Error

Solution code:
# -*- coding: utf-8 -*-
"""
Created on Sat Jul 14 10:14:13 2018
ALDS1_11_D
@author: maezawa
"""
import sys
sys.setrecursionlimit(100000)

n, m = list(map(int, input().split()))
v = [-1 for _ in range(n)]
stack = []
adj = [[] for _ in range(n)]
for i in range(m):
    s, t = list(map(int, input().split()))
    adj[s].append(t)
    adj[t].append(s)
#print(*adj, sep='\n')
def dfs(u, color):
    if v[u] > 0:
        return 0
    v[u] = color
    #print(u, current, stack)
    for k in adj[u]:
        if v[k] > 0:
            continue
        dfs(k, color)
    return 1

color = 1
for start in range(n):
    if dfs(start, color) == 1:
        color += 1
#for i in range(n):        
#    print('color:{} for node:{}'.format(i, v[i]))

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

Submission status: Runtime Error

Solution code:
# -*- coding: utf-8 -*-


class LinkedList:
    def __init__(self, n):
        self.n = n
        self.ll = [[] for _ in range(self.n)]

    def link(self, u, v, direction=False):
        self.ll[u].append(v)
        if not direction:
            self.ll[v].append(u)

    def dfs(self):
        self.cc = [None] * self.n

        color = 1
        for u in range(self.n):
            if not self.cc[u]:
                self.dfs_visit(u, color)
                color += 1

    def dfs_visit(self, u, color):
        self.cc[u] = color
        for v in self.ll[u]:
            if not self.cc[v]:
                self.dfs_visit(v, color)

    def check(self, u, v):
        if self.cc[u] == self.cc[v]:
            print('yes')
        else:
            print('no')


if __name__ == '__main__':
    n, m = map(int, input().split())
    ll = LinkedList(n)

    for _ in range(m):
        u, v = map(int, input().split())
        ll.link(u, v)
    ll.dfs()

    q = int(input())
    for _ in range(q):
        u, v = map(int, input().split())
        ll.check(u, v)

Submission status: Runtime Error

Solution code:
def dfs(s):
    global t
    if s == t:
        return True
    DP[s]=1
    for i in F[s]:
        if not DP[i]:
            if dfs(i):
                return True
    return False
    
n,m = [int(i) for i in input().split()]
F = [{} for i in range(n)]
for _ in range(m):
    i,j = [int(i) for i in input().split()]
    F[i][j] = 1
    F[j][i] = 1
q = int(input())
for i in range(q):
    DP = [0]*n
    s,t = [int(i) for i in input().split()]
    if dfs(s):
        print("yes")
    else:
        print("no")

Submission status: Runtime Error

Solution code:
import sys
sys.setrecursionlimit(10000)
def dfs(s):
    global t
    if s == t:
        return True
    DP[s]=1
    for i in F[s]:
        if not DP[i]:
            if dfs(i):
                return True
    return False
    
n,m = [int(i) for i in input().split()]
F = [{} for i in range(n)]
for _ in range(m):
    i,j = [int(i) for i in input().split()]
    F[i][j] = 1
    F[j][i] = 1
q = int(input())
for i in range(q):
    DP = [0]*n
    s,t = [int(i) for i in input().split()]
    if dfs(s):
        print("yes")
    else:
        print("no")

Submission status: Runtime Error

Solution code:
#coding: utf-8
global b

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

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


def search(a,target):
    if a == target:
        print("yes")
        return False
    for member in List[a]:
        if color[member] == "white":
            color[member] = "black"
            if search(member, target) == False:
                return False
    return True
            
p = int(input())
for i in range(p):
    color = ["white" for i in range(n)]
    a, target = map(int,input().split())
    color[a] = "black"
    b = search(a, target)
    if b :
        print("no")

Submission status: Runtime Error

Solution code:
from sys import stdin

def read_graph(n, k):
    A = [ [] for _ in range(n) ]
    for _ in range(k):
        line = stdin.readline().strip().split()
        A[int(line[0])].append(int(line[1]))
        A[int(line[1])].append(int(line[0]))
    return A

def dfs_ctrl(n, A, s, t):
    color = ["WHITE"] * n
    d = [0] * n
    f = [0] * n
    time = 0

    def dfs(u):
        nonlocal color
        nonlocal time
        color[u] = "GRAY"
        time += 1
        d[u] = time

        for v in A[u]:
            if color[v] == "WHITE":
                dfs(v)
        color[u] = "BLACK"
        time += 1
        f[u] = time

    dfs(s)
    if d[t] != 0:
        print("yes")
    else:
        print("no")

def read_and_print_connection(m):
    for _ in range(m):
        line = stdin.readline().strip().split()
        s = int(line[0])
        t = int(line[1])
        dfs_ctrl(n, A, s, t)

n, k = [int(i) for i in input().split()]
A = read_graph(n, k)
m = int(input())
read_and_print_connection(m)

Submission status: Runtime Error

Solution code:
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)

Submission status: Runtime Error

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

global visited 
visited = [0 for _ in range(n)]

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

def dfs(node_id):
  
  for ad_node in graph[node_id]:
    if visited[ad_node] == 1:
      continue
    visited[ad_node] = 1
    dfs(ad_node)

if __name__ == "__main__":
  input_graph(m)
  q_num = int(input())
  for _ in range(q_num):
    visited = [0 for _ in range(n)]
    s, t = map(int, input().split())
    dfs(s)
    if visited[t]:
      print("yes")
    else:
      print("no")

Submission status: Runtime Error

Solution code:
sys.setrecursionlimit(10000)
n, m = map(int, input().split())
graph = [[] for _ in range(n)]

global visited 
visited = [0 for _ in range(n)]

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

def dfs(node_id):
  
  for ad_node in graph[node_id]:
    if visited[ad_node] == 1:
      continue
    visited[ad_node] = 1
    dfs(ad_node)

if __name__ == "__main__":
  input_graph(m)
  q_num = int(input())
  for _ in range(q_num):
    visited = [0 for _ in range(n)]
    s, t = map(int, input().split())
    dfs(s)
    if visited[t]:
      print("yes")
    else:
      print("no")

Submission status: Runtime Error

Solution code:
import sys
sys.setrecursionlimit(10000)
n, m = map(int, input().split())
graph = [[] for _ in range(n)]

global visited 
visited = [0 for _ in range(n)]

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

def dfs(node_id):
  
  for ad_node in graph[node_id]:
    if visited[ad_node] == 1:
      continue
    visited[ad_node] = 1
    dfs(ad_node)

if __name__ == "__main__":
  input_graph(m)
  q_num = int(input())
  for _ in range(q_num):
    visited = [0 for _ in range(n)]
    s, t = map(int, input().split())
    dfs(s)
    if visited[t]:
      print("yes")
    else:
      print("no")

Submission status: Runtime Error

Solution code:
import sys
sys.setrecursionlimit(1000000)
n, m = map(int, input().split())
graph = [[] for _ in range(n)]

global visited 
visited = [0 for _ in range(n)]
global Q, S, T

S = [0] #訪れた順
T = []
visited[0] = 1 #開始位置はすでに訪れたことにする

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

def dfs():
  global Q, S
  while Q:
    node_id = Q.pop()

    for ad_node in graph[node_id]:
      if visited[ad_node] == 1:
        continue
      visited[ad_node] = 1
      S.append(ad_node)
      Q.append(ad_node)


"""
def dfs(node_id):
  
  for ad_node in graph[node_id]:
    if visited[ad_node] == 1:
      continue
    visited[ad_node] = 1
    dfs(ad_node)
"""
if __name__ == "__main__":
  input_graph(m)
  q_num = int(input())
  for _ in range(q_num):
    visited = [0 for _ in range(n)]
    s, t = map(int, input().split())
    Q = deque([s])
    dfs()
    if visited[t]:
      print("yes")
    else:
      print("no")

Submission status: Runtime Error

Solution code:
#!/usr/bin/python3
n, m = map(int, input().split())

e = [None] * n

for i in range(m):
    s, t = map(int, input().split())
    if e[s] == None and e[t] == None:
        a = {s, t}
        e[s] = e[t] = a
    elif e[s] == None:
        e[t].add(s)
        e[s] = e[t]
    elif e[t] == None:
        e[s].add(t)
        e[t] = e[s]
    else:
        a = e[s] | e[t]
        for j in a:
            e[j] = a

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

Submission status: Runtime Error

Solution code:
#!/usr/bin/python3

def set_color(i, ci, e, color):
    color[i] = ci
    for next_i in e[i]:
        if color[next_i] != ci:
            set_color(next_i, ci, e, color)

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')

Submission status: Runtime Error

Solution code:
class node:
    def __init__(self, num):
        self.number     = num
        self.group      = 0
        self.link_node  = []
        self.is_serched = False

def DFS(node, group_num):
    node.is_serched = True
    node.group      = group_num
    for item in node.link_node:
        if item.is_serched == False:
            DFS(item, group_num)

n ,m = map(int, raw_input().split())
node_list = [None] * (n)

for i in xrange(n):
    node_list[i] = node(i)

for _ in xrange(m):
    s, t = map(int, raw_input().split())
    node_list[s].link_node.append(node_list[t])
    node_list[t].link_node.append(node_list[s])

group_num = 1
for item in node_list:
    if item.is_serched == False:
        DFS(item, group_num)
        group_num = group_num + 1

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

Submission status: Runtime Error

Solution code:
def DFS(s):
    flag[s] = 1
    F[group] += s
    for i in range(n):
        if G[s][i] == 1:
            if flag[i] == 0:
                DFS(i)
 

n, m = map(int, input().split())
G = [[0 for i in range(n)] for j in range(n)]
for i in range(m):
    s, t = map(int, input().split())
    G[s][t] = 1
    G[t][s] = 1

F = []
flag = [0 for i in range(n)]
group = 0
for i in range(n):
    if flag[i] == 0:
        F.append([])
        DFS(i)
        group += 1

q = int(input())
ans = ["no" for i in range(q)]
for i in range(q):
    s, t = map(int, input().split())
    for friends in F:
        if s in friends and t in friends:
            ans[i] = "yes"

for i in range(q):
    print(ans[i])

Submission status: Runtime Error

Solution code:
def DFS(s):
    flag[s] = 1
    F[group] = F[group] + s
    for i in range(n):
        if G[s][i] == 1:
            if flag[i] == 0:
                DFS(i)
 

n, m = map(int, input().split())
G = [[0 for i in range(n)] for j in range(n)]
for i in range(m):
    s, t = map(int, input().split())
    G[s][t] = 1
    G[t][s] = 1

F = []
flag = [0 for i in range(n)]
group = 0
for i in range(n):
    if flag[i] == 0:
        F.append([])
        DFS(i)
        group += 1

q = int(input())
ans = ["no" for i in range(q)]
for i in range(q):
    s, t = map(int, input().split())
    for friends in F:
        if s in friends and t in friends:
            ans[i] = "yes"

for i in range(q):
    print(ans[i])

Submission status: Runtime Error

Solution code:
entry = map(int, raw_input())
n = entry[0]
m = entry[1]
A = [] * n
for i in range(m):
    entry = map(int, raw_input())
    A[entry[0]].append(entry[1])
    A[entry[1]].append(entry[0])

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

Submission status: Runtime Error

Solution code:
entry = map(int, raw_input())
n = entry[0]
m = entry[1]

color = [0] * n
affil = [0] * n
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)
    return group_num

A = range(n)
for i in A:
    A[i] = list()
for i in range(m):
    entry = friends[i]
    s = entry[0]
    t = entry[1]
    A[s].append(t)
    A[t].append(s)

group_num = -1
for i in range(n):
    if color[i] == 0:
        Q = [i]
        affil[i] = group_num + 1
        group_num = BFS(i, group_num + 1)

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

Submission status: Runtime Error

Solution code:

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)
    return group_num

A = range(n)
for i in A:
    A[i] = list()
for i in range(m):
    entry = map(int, raw_input())
    s = entry[0]
    t = entry[1]
    A[s].append(t)
    A[t].append(s)

entry = map(int, raw_input())
n = entry[0]
m = entry[1]

color = [0] * n
affil = [0] * n

group_num = -1
for i in range(n):
    if color[i] == 0:
        Q = [i]
        affil[i] = group_num + 1
        group_num = BFS(i, group_num + 1)

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

Submission status: Runtime Error

Solution code:

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)
    return group_num

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

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

Submission status: Runtime Error

Solution code:
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)
    return group_num

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

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