Ответ к предыдущей задаче для новичков.

def longest_substring(s):
    n = len(s)
    substrings = set()
    max_substring = None
    max_count = 0
    for i in range(n):
        for j in range(i + 1, n + 1):
            substr = s[i:j]
            if substr in substrings:
                count = s.count(substr)
                if count > max_count:
                    max_substring = substr
                    max_count = count
                elif count == max_count and len(substr) > len(max_substring):
                    max_substring = substr
            else:
                substrings.add(substr)
    return (max_substring, max_count)

#pythonзадача #coбес