BOJ16472 고냥이

https://www.acmicpc.net/problem/16472

16472번: 고냥이

 

import java.util.*;
import java.io.*;
public class Main
{   
    

	public static void main(String[] args) throws IOException {
		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
		
		int n = Integer.parseInt(br.readLine());
        String word = br.readLine();
		
		HashMap<Character,Integer> alpha = new HashMap();
		int count_alpha=0;
        int ans=0;
        int right=0;
        for(int left=0; left<word.length();left++){
            while(right<word.length() && count_alpha<=n){
                alpha.put(word.charAt(right),alpha.getOrDefault(word.charAt(right),0)+1);
                if(alpha.get(word.charAt(right))==1){
                    count_alpha++;    
                }
                if(count_alpha<=n){
                    ans = Math.max(ans,right-left+1);    
                }
                right++;
            }
            alpha.put(word.charAt(left),alpha.get(word.charAt(left))-1);
            if(alpha.get(word.charAt(left))==0){
                count_alpha-=1;
            }
            
            
        }
		
		System.out.println(ans);
	}
}

import java.util.Scanner;

class Main
{
    static int[] currentAlphabetFrequency = new int[26];
    static int currentUniqueAlphabetCount = 0;

    static void increaseFrequency(char alphabet) {
        if (currentAlphabetFrequency[alphabet - 'a']++ == 0)
            currentUniqueAlphabetCount++;
    }

    static void decreaseFrequency(char alphabet) {
        if (--currentAlphabetFrequency[alphabet - 'a'] == 0)
            currentUniqueAlphabetCount--;
    }

    public static void main (String[] args) {
        Scanner sc = new Scanner(System.in);

        int N = sc.nextInt();
        char[] nyang = sc.next().toCharArray();
        int nextIndex = 0;
        int maxLength = 0;
        for (int i = 0; i < nyang.length; i++) {
            while (nextIndex < nyang.length) {
                increaseFrequency(nyang[nextIndex++]);
                if (currentUniqueAlphabetCount > N) {
                    decreaseFrequency(nyang[--nextIndex]);
                    break;
                }
            }
            maxLength = Math.max(maxLength, nextIndex - i);
            decreaseFrequency(nyang[i]);
        }
        System.out.println(maxLength);
    }
}