Building Teams

import sys

class Node:
    def __init__(self):
        self.connected = []
        self.been = False
        self.team = 0

    def connect(self, other):
        self.connected.append(other)
        other.connected.append(self)

    def visit_group(self):
        if self.been:
            return
        self.been = True
        if self.team == 0:
            self.team = 1
        for c in self.connected:
            if self.team == c.team:
                return False
            if self.team == 1:
                c.team = 2
            else:
                c.team = 1
            c.visit_group()

n, m = [int(i) for i in input().split()]
nodes = [Node() for _ in range(n)]
sys.setrecursionlimit(n + 100)

for _ in range(m):
    a, b = [int(i) - 1 for i in input().split()]
    nodes[a].connect(nodes[b])

for i in range(n):
    res = nodes[i].visit_group()
    if res == False:
        print("IMPOSSIBLE")
        break
else:
    for node in nodes:
        print(node.team, end=" ")

Test 1

Verdict: ACCEPTED

Test 2

Verdict: ACCEPTED

Test 3

Verdict: ACCEPTED

Test 4

Verdict: ACCEPTED

Test 5

Verdict: WRONG ANSWER

Test 6

Verdict: TIME LIMIT EXCEEDED

Test 7

Verdict: TIME LIMIT EXCEEDED

Test 8

Verdict: TIME LIMIT EXCEEDED

Test 9

Verdict: ACCEPTED

Test 10

Verdict: ACCEPTED

Test 11

Verdict: ACCEPTED

Test 12

Verdict: WRONG ANSWER