CSES - Aalto Competitive Programming 2026 - wk2 - Mon

Submission details
Task:	Building Teams
Sender:	aalto26bm_023
Submission time:	2026-09-07 17:49:56 +0300
Language:	Python3 (CPython3)
Status:	READY
Result:	RUNTIME ERROR

Test results
test	verdict	time
#1	ACCEPTED	0.02 s	details
#2	ACCEPTED	0.02 s	details
#3	ACCEPTED	0.02 s	details
#4	ACCEPTED	0.02 s	details
#5	ACCEPTED	0.02 s	details
#6	RUNTIME ERROR	0.89 s	details
#7	RUNTIME ERROR	0.89 s	details
#8	RUNTIME ERROR	0.89 s	details
#9	RUNTIME ERROR	0.88 s	details
#10	ACCEPTED	0.88 s	details
#11	ACCEPTED	0.02 s	details
#12	ACCEPTED	0.02 s	details

Code

n, m = input().split()
m, n = int(m), int(n)
d = {}
for i in range(m):
    a, b = input().split()
    a, b = int(a)-1, int(b)-1
    if a not in d:
        d[a]=[b]
    else : 
        d[a].append(b)
    if b not in d:
        d[b]=[a]
    else : 
        d[b].append(a)

# visited = [False]*n
colours = [0]*n

# colour = 1 or 2, or 0 if not visited
def dfs(start, colour):
    if colours[start]==colour:
        return 0 # Ok with colour
    if colours[start]== 3-colour:
        return -1
    colours[start]=colour
    # visited[start]=True
    for node in d[start]:
        if dfs(node, 3-colour) == -1:
            return -1

for node in range(n):
    # print(node)
    if colours[node]==0:
        if dfs(node, 1)==-1:
            print("IMPOSSIBLE")
            exit()
for c in colours:
    print(c, end=' ')
print()

Test details

Test 1

Verdict: ACCEPTED

input
`10 20 3 4 8 10 3 7 1 8 ...` view save

correct output
`1 1 1 2 2 1 2 2 2 1` view save

user output
`1 1 1 2 2 1 2 2 2 1` view save

Test 2

Verdict: ACCEPTED

input
`10 20 1 3 8 10 2 4 6 8 ...` view save

correct output
`1 1 2 2 1 1 1 2 1 1` view save

user output
`1 1 2 2 1 1 1 2 1 1` view save

Test 3

Verdict: ACCEPTED

input
`10 20 7 10 3 10 9 10 2 10 ...` view save

correct output
`1 2 2 1 1 1 2 1 2 1` view save

user output
`1 2 2 1 1 1 2 1 2 1` view save

Test 4

Verdict: ACCEPTED

input
`10 20 2 4 2 10 7 10 4 6 ...` view save

correct output
`1 2 1 1 2 2 2 1 2 1` view save

user output
`1 2 1 1 2 2 2 1 2 1` view save

Test 5

Verdict: ACCEPTED

input
`10 20 3 5 8 10 9 10 1 8 ...` view save

correct output
`IMPOSSIBLE` view save

user output
`IMPOSSIBLE` view save

Test 6

Verdict: RUNTIME ERROR

input
`100000 200000 47355 96505 90709 92058 735 80715 91802 94265 ...` view save

correct output
`1 2 2 1 2 1 1 1 2 2 1 2 1 1 1 ...` view save

user output
(empty)

Error:

Traceback (most recent call last):
  File "/box/input/code.py", line 34, in <module>
    if dfs(node, 1)==-1:
       ^^^^^^^^^^^^
  File "/box/input/code.py", line 28, in dfs
    if dfs(node, 3-colour) == -1:
       ^^^^^^^^^^^^^^^^^^^
  File "/box/input/code.py", line 28, in dfs
    if dfs(node, 3-colour) == -1:
       ^^^^^^^^^^^^^^^^^^^
  File "/box/input/code.py", line 28, in dfs
    if dfs(node, 3-colour) == -1:
       ^^^^^^^^^^^^^^^^^^^
  [Previous line repeated 996 more times]
RecursionError: maximum recursion depth exceeded

Test 7

Verdict: RUNTIME ERROR

input
`100000 200000 59991 95794 95150 96051 78453 94730 90411 95523 ...` view save

correct output
`1 1 1 2 2 1 1 2 1 2 1 2 2 2 1 ...` view save

user output
(empty)

Error:

Traceback (most recent call last):
  File "/box/input/code.py", line 34, in <module>
    if dfs(node, 1)==-1:
       ^^^^^^^^^^^^
  File "/box/input/code.py", line 28, in dfs
    if dfs(node, 3-colour) == -1:
       ^^^^^^^^^^^^^^^^^^^
  File "/box/input/code.py", line 28, in dfs
    if dfs(node, 3-colour) == -1:
       ^^^^^^^^^^^^^^^^^^^
  File "/box/input/code.py", line 28, in dfs
    if dfs(node, 3-colour) == -1:
       ^^^^^^^^^^^^^^^^^^^
  [Previous line repeated 996 more times]
RecursionError: maximum recursion depth exceeded

Test 8

Verdict: RUNTIME ERROR

input
`100000 200000 89827 96402 65137 86792 80965 94708 19479 48078 ...` view save

correct output
`1 2 1 1 2 1 2 2 2 1 2 1 1 2 1 ...` view save

user output
(empty)

Error:

Traceback (most recent call last):
  File "/box/input/code.py", line 34, in <module>
    if dfs(node, 1)==-1:
       ^^^^^^^^^^^^
  File "/box/input/code.py", line 28, in dfs
    if dfs(node, 3-colour) == -1:
       ^^^^^^^^^^^^^^^^^^^
  File "/box/input/code.py", line 28, in dfs
    if dfs(node, 3-colour) == -1:
       ^^^^^^^^^^^^^^^^^^^
  File "/box/input/code.py", line 28, in dfs
    if dfs(node, 3-colour) == -1:
       ^^^^^^^^^^^^^^^^^^^
  [Previous line repeated 996 more times]
RecursionError: maximum recursion depth exceeded

Test 9

Verdict: RUNTIME ERROR

input
`100000 200000 72952 83723 66197 70052 2949 52160 55753 95651 ...` view save

correct output
`1 1 2 2 2 1 1 2 2 2 2 2 1 2 1 ...` view save

user output
(empty)

Error:

Traceback (most recent call last):
  File "/box/input/code.py", line 34, in <module>
    if dfs(node, 1)==-1:
       ^^^^^^^^^^^^
  File "/box/input/code.py", line 28, in dfs
    if dfs(node, 3-colour) == -1:
       ^^^^^^^^^^^^^^^^^^^
  File "/box/input/code.py", line 28, in dfs
    if dfs(node, 3-colour) == -1:
       ^^^^^^^^^^^^^^^^^^^
  File "/box/input/code.py", line 28, in dfs
    if dfs(node, 3-colour) == -1:
       ^^^^^^^^^^^^^^^^^^^
  [Previous line repeated 996 more times]
RecursionError: maximum recursion depth exceeded

Test 10

Verdict: ACCEPTED

input
`100000 200000 38942 96755 70049 82663 7746 72732 87819 99029 ...` view save

correct output
`IMPOSSIBLE` view save

user output
`IMPOSSIBLE` view save

Test 11

Verdict: ACCEPTED

input
`5 4 1 2 3 4 4 5 5 3` view save

correct output
`IMPOSSIBLE` view save

user output
`IMPOSSIBLE` view save

Test 12

Verdict: ACCEPTED

input
`4 5 1 2 1 4 2 3 2 4 ...` view save

correct output
`IMPOSSIBLE` view save

user output
`IMPOSSIBLE` view save

Aalto Competitive Programming 2026 - wk2 - Mon

Building Teams

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 (aalto26bm_023)