Building Teams

def function(n, m, friends):
    teams = [0] * n
    teams[0] = 1
    sorted_friends = sorted(friends)
    for friend in sorted_friends:
        a = friend[0] - 1
        b = friend[1] - 1
        if teams[a] == 0 and teams[b] == 0:
            teams[a] = 1
            teams[b] = 2
        elif (teams[a] == 1 and teams[b] == 1) or (teams[a] == 2 and teams[b] == 2):
            return []
        elif (teams[a] == 0 and teams[b] == 1):
            teams[a] = 2
        elif (teams[a] == 0 and teams[b] == 2):
            teams[a] = 1
        elif (teams[b] == 0 and teams[a] == 1):
            teams[b] = 2
        elif (teams[b] == 0 and teams[a] == 2):
            teams[b] = 1

    return teams


def main():
    n, m = map(int, input().split())
    graph = [[] for _ in range(n+1)]
    friends = []

    for _ in range(m):
        a, b = map(int, input().split())
        graph[a].append(b)
        graph[b].append(a)
        friends.append([a, b])

    # applicants = list(map(int, input().split()))
    # apartments = list(map(int, input().split()))



    results = function(n, m, friends)
    if results == []:
        print("IMPOSSIBLE")
        return
    for result in results:
        print(result, end=" ")



if __name__ == "__main__":
    main()

Test 1

Verdict: ACCEPTED

Test 2

Verdict: ACCEPTED

Test 3

Verdict: WRONG ANSWER

Test 4

Verdict: ACCEPTED

Test 5

Verdict: ACCEPTED

Test 6

Verdict: TIME LIMIT EXCEEDED

Test 7

Verdict: TIME LIMIT EXCEEDED

Test 8

Verdict: TIME LIMIT EXCEEDED

Test 9

Verdict: TIME LIMIT EXCEEDED

Test 10

Verdict: TIME LIMIT EXCEEDED

Test 11

Verdict: ACCEPTED

Test 12

Verdict: ACCEPTED