Envío 3458

Código

def longest_substring_k_distinct(s, k = 26):
    if k == 26:
        return len(s)
    
    longest_substring_size = 0
    window_start = 0
    char_freq = {}

    for window_end, current in enumerate(s):
        if current in char_freq:
            char_freq[current] = char_freq[current] + 1
        else: 
            char_freq[current] = 1

        while len(char_freq) > k:
            prev = s[window_start]

            if char_freq[prev] == 1:
                char_freq.pop(prev)
            else:
                char_freq[prev] = char_freq[prev] - 1

            window_start += 1

        longest_substring_size = max(longest_substring_size, window_end - window_start + 1)

    return longest_substring_size

s = input()
k = int(input())
        
print(longest_substring_k_distinct(s, k))