?백준 | 좋은수열

백준 좋은수열

import sys

def is_good_sequence(seq):
    length = len(seq)
    for i in range(1, length // 2 + 1):
        if seq[-i:] == seq[(-2) * i:-i]:
            return False
    return True

def backtracking(seq):
    if len(seq) == n:
        print(''.join(map(str, seq)))
        exit(0)

    for num in range(1, 4):
        seq.append(num)

        if is_good_sequence(seq):
            backtracking(seq)
        
        seq.pop()

n = int(sys.stdin.readline())

backtracking([])