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Aalto Competitive Programming 2026 - wk2 - Homework

Connect cities

  • Start: 2026-09-02 18:00:00
  • End: 2026-09-09 16:15:00
Submission details
Task:Connect cities
Sender:aalto26bh_020
Submission time:2026-09-02 20:43:50 +0300
Language:Python3 (PyPy3)
Status:READY
Result:
Test results
testverdicttime
#1ACCEPTED0.04 sdetails
#2ACCEPTED0.04 sdetails
#3ACCEPTED0.04 sdetails
#4ACCEPTED0.04 sdetails
#5ACCEPTED0.04 sdetails
#60.35 sdetails
#70.35 sdetails
#80.35 sdetails
#90.35 sdetails
#100.35 sdetails
#11ACCEPTED0.11 sdetails
#12ACCEPTED0.04 sdetails

Code

prob_input = input().split(" ")

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

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

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

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

components = []
visited = [False for _ in range(num_cities)]


def search_city(city_index):
    if visited[city_index]:
        return

    visited[city_index] = True
    for neighbor_index in cities[city_index]:
        search_city(neighbor_index)


for i in range(len(cities)):
    if visited[i]:
        continue

    components.append(i)
    search_city(i)

print(len(components) - 1)
for i in range(len(components) - 1):
    print(components[i] + 1, components[i + 1] + 1)

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
2 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
4 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:

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(i)
  File "/box/input/code.py", line 24, in search_city
    search_city(neighbor_index)
  File "/box/input/code.py", line 24, in search_city
    search_city(neighbor_index)
  File "/box/input/code.py", line 24, in search_city
    search_city(neighbor_index)
  [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:

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(i)
  File "/box/input/code.py", line 24, in search_city
    search_city(neighbor_index)
  File "/box/input/code.py", line 24, in search_city
    search_city(neighbor_index)
  File "/box/input/code.py", line 24, in search_city
    search_city(neighbor_index)
  [Previous line repeated 1685 more times]
RecursionError: maximum recursion depth exceeded

Test 8

Verdict:

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(i)
  File "/box/input/code.py", line 24, in search_city
    search_city(neighbor_index)
  File "/box/input/code.py", line 24, in search_city
    search_city(neighbor_index)
  File "/box/input/code.py", line 24, in search_city
    search_city(neighbor_index)
  [Previous line repeated 1470 more times]
  File "/box/input/code.py", line 18, in search_city
    def search_city(city_index):
RecursionError: maximum recursion depth exceeded

Test 9

Verdict:

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(i)
  File "/box/input/code.py", line 24, in search_city
    search_city(neighbor_index)
  File "/box/input/code.py", line 24, in search_city
    search_city(neighbor_index)
  File "/box/input/code.py", line 24, in search_city
    search_city(neighbor_index)
  [Previous line repeated 1685 more times]
RecursionError: maximum recursion depth exceeded

Test 10

Verdict:

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(i)
  File "/box/input/code.py", line 24, in search_city
    search_city(neighbor_index)
  File "/box/input/code.py", line 24, in search_city
    search_city(neighbor_index)
  File "/box/input/code.py", line 24, in search_city
    search_city(neighbor_index)
  [Previous line repeated 1685 more times]
RecursionError: maximum recursion depth exceeded

Test 11

Verdict: ACCEPTED

input
100000 1
1 2
view save

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

user output
99998
1 3
3 4
4 5
5 6
...
view save

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
2 7
view save

Tasks

A Connect citiesB Apartments

Submissions (aalto26bh_020)

2026-09-02 21:25:39 2026-09-02 21:18:28 2026-09-02 21:17:02 2026-09-02 21:11:40 2026-09-02 21:11:10 2026-09-02 21:10:51 2026-09-02 21:08:36 2026-09-02 21:07:57 2026-09-02 21:04:15 2026-09-02 20:43:50 2026-09-02 20:36:40