CSES - Aalto Competitive Programming 2026 - wk2 - Homework

Submission details
Task:	Connect cities
Sender:	aalto26bh_020
Submission time:	2026-09-02 21:18:28 +0300
Language:	Python3 (PyPy3)
Status:	READY
Result:	RUNTIME ERROR

Test results
test	verdict	time
#1	ACCEPTED	0.04 s	details
#2	ACCEPTED	0.04 s	details
#3	ACCEPTED	0.04 s	details
#4	ACCEPTED	0.04 s	details
#5	ACCEPTED	0.04 s	details
#6	RUNTIME ERROR	0.35 s	details
#7	RUNTIME ERROR	0.35 s	details
#8	RUNTIME ERROR	0.35 s	details
#9	RUNTIME ERROR	0.35 s	details
#10	RUNTIME ERROR	0.35 s	details
#11	TIME LIMIT EXCEEDED	--	details
#12	ACCEPTED	0.04 s	details

Code

inp = input().split(" ")

num_cities, num_roads = (int(inp[0]), int(inp[1]))

cities = [[] for _ in range(num_cities)]

for i in range(num_roads):
    inp = input().split(" ")
    a, b = (int(inp[0]), int(inp[1]))

    cities[a - 1].append(b - 1)
    cities[b - 1].append(a - 1)

visited = []
components = []


def search_city(city_index):
    if city_index in visited:
        return

    visited.append(city_index)
    for neighbor in cities[city_index]:
        search_city(neighbor)


for city_index in range(len(cities)):
    if city_index in visited:
        continue

    components.append(city_index + 1)
    search_city(city_index)


if len(components) > 0:
    a = components[0]
    print(len(components) - 1)

    for i in range(1, len(components)):
        print(a, components[i])
else:
    print(0)

Test details

Test 1

Verdict: ACCEPTED

input
`10 10 2 5 5 6 1 4 6 8 ...` view save

correct output
`2 1 2 2 7` view save

user output
`2 1 2 1 7` view save

Test 2

Verdict: ACCEPTED

input
`10 10 3 9 6 8 9 10 7 8 ...` view save

correct output
`2 1 4 4 5` view save

user output
`2 1 4 1 5` view save

Test 3

Verdict: ACCEPTED

input
`10 10 7 9 1 7 1 3 3 4 ...` view save

correct output
`0` view save

user output
`0` view save

Test 4

Verdict: ACCEPTED

input
`10 10 4 8 5 9 4 9 2 7 ...` view save

correct output
`1 1 3` view save

user output
`1 1 3` view save

Test 5

Verdict: ACCEPTED

input
`10 10 4 9 2 4 7 10 1 8 ...` view save

correct output
`0` view save

user output
`0` view save

Test 6

Verdict: RUNTIME ERROR

input
`100000 200000 7233 22146 94937 96203 6133 10731 98737 99193 ...` view save

correct output
`4785 1 2 2 3 3 4 4 5 ...` view save

user output
(empty)

Error:

Traceback (most recent call last):
  File "/box/input/code.py", line 32, in <module>
    search_city(city_index)
  File "/box/input/code.py", line 24, in search_city
    search_city(neighbor)
  File "/box/input/code.py", line 24, in search_city
    search_city(neighbor)
  File "/box/input/code.py", line 24, in search_city
    search_city(neighbor)
  [Previous line repeated 1538 more times]
  File "/box/input/code.py", line 18, in search_city
    def search_city(city_index):
RecursionError: maximum recursion depth exceeded

Test 7

Verdict: RUNTIME ERROR

input
`100000 200000 92950 93575 24401 88897 41796 99364 47106 50330 ...` view save

correct output
`4868 1 2 2 7 7 9 9 15 ...` view save

user output
(empty)

Error:

Traceback (most recent call last):
  File "/box/input/code.py", line 32, in <module>
    search_city(city_index)
  File "/box/input/code.py", line 24, in search_city
    search_city(neighbor)
  File "/box/input/code.py", line 24, in search_city
    search_city(neighbor)
  File "/box/input/code.py", line 24, in search_city
    search_city(neighbor)
  [Previous line repeated 1684 more times]
  File "/box/input/code.py", line 22, in search_city
    visited.append(city_index)
RecursionError: maximum recursion depth exceeded

Test 8

Verdict: RUNTIME ERROR

input
`100000 200000 15637 76736 79169 98809 4382 86557 73383 77029 ...` view save

correct output
`4683 1 9 9 20 20 27 27 28 ...` view save

user output
(empty)

Error:

Traceback (most recent call last):
  File "/box/input/code.py", line 32, in <module>
    search_city(city_index)
  File "/box/input/code.py", line 24, in search_city
    search_city(neighbor)
  File "/box/input/code.py", line 24, in search_city
    search_city(neighbor)
  File "/box/input/code.py", line 24, in search_city
    search_city(neighbor)
  [Previous line repeated 1492 more times]
RecursionError: maximum recursion depth exceeded

Test 9

Verdict: RUNTIME ERROR

input
`100000 200000 47932 66981 86401 99942 4353 27841 60492 67345 ...` view save

correct output
`4807 1 6 6 7 7 11 11 12 ...` view save

user output
(empty)

Error:

Traceback (most recent call last):
  File "/box/input/code.py", line 32, in <module>
    search_city(city_index)
  File "/box/input/code.py", line 24, in search_city
    search_city(neighbor)
  File "/box/input/code.py", line 24, in search_city
    search_city(neighbor)
  File "/box/input/code.py", line 24, in search_city
    search_city(neighbor)
  [Previous line repeated 1684 more times]
  File "/box/input/code.py", line 22, in search_city
    visited.append(city_index)
RecursionError: maximum recursion depth exceeded

Test 10

Verdict: RUNTIME ERROR

input
`100000 200000 6554 44548 76413 98555 5447 59589 70166 74434 ...` view save

correct output
`4786 1 2 2 18 18 21 21 27 ...` view save

user output
(empty)

Error:

Traceback (most recent call last):
  File "/box/input/code.py", line 32, in <module>
    search_city(city_index)
  File "/box/input/code.py", line 24, in search_city
    search_city(neighbor)
  File "/box/input/code.py", line 24, in search_city
    search_city(neighbor)
  File "/box/input/code.py", line 24, in search_city
    search_city(neighbor)
  [Previous line repeated 1684 more times]
  File "/box/input/code.py", line 22, in search_city
    visited.append(city_index)
RecursionError: maximum recursion depth exceeded

Test 11

Verdict: TIME LIMIT EXCEEDED

input
`100000 1 1 2` view save

correct output
`99998 1 3 3 4 4 5 5 6 ...` view save

user output
(empty)

Test 12

Verdict: ACCEPTED

input
`10 9 2 5 5 6 1 4 6 8 ...` view save

correct output
`2 1 2 2 7` view save

user output
`2 1 2 1 7` view save

Aalto Competitive Programming 2026 - wk2 - Homework

Connect cities

Code

Test details

Test 1

Test 2

Test 3

Test 4

Test 5

Test 6

Test 7

Test 8

Test 9

Test 10

Test 11

Test 12

Tasks

Submissions (aalto26bh_020)