Envío 4916

Código

import java.util.*; 

public class Main {
    public static void main(String[] args) {
        // Substring más larga con máximo K caracteres diferentes
        // "codeo"
        // 3
        Scanner scanner = new Scanner(System.in);
        final String input = scanner.next();
        final int k = scanner.nextInt();
        
        //Solution here boy
        int result = 0;
        int i = 0;
        final Map<Character, Integer> freqMap = new HashMap<>();
        
        for(int j = 0; j < input.length(); j++) {
            char rightChar = input.charAt(j);
            freqMap.put(rightChar, freqMap.getOrDefault(rightChar, 0) + 1);
            
            while(freqMap.size() > k) {
                char leftChar = input.charAt(i);
                freqMap.put(leftChar, freqMap.getOrDefault(leftChar, 0) - 1);
                if(freqMap.get(leftChar) == 0) {
                    freqMap.remove(leftChar);
                }
                i++;
            }
            
            result = Math.max(result, j - i + 1);
        }
        
        System.out.println(result);
        scanner.close();
    }
}