알고리즘입문(Java) - HashMap,TreeSet 3.매출액의 종류(Hash, sliding window)

 

(풀이)

import java.util.*;
class Main {
    public ArrayList<Integer> solution(int n, int k, int[] arr){
        ArrayList<Integer> answer = new ArrayList<>();
        HashMap<Integer, Integer> HM = new HashMap<>();
        for(int i=0; i<k-1; i++){
            HM.put(arr[i], HM.getOrDefault(arr[i], 0)+1);
        }
        int lt=0;
        for(int rt=k-1; rt<n; rt++){
            HM.put(arr[rt], HM.getOrDefault(arr[rt], 0)+1);
            answer.add(HM.size());
            HM.put(arr[lt], HM.get(arr[lt])-1);
            if(HM.get(arr[lt])==0) HM.remove(arr[lt]);
            lt++;
        }
        return answer;
    }

    public static void main(String[] args){
        Main T = new Main();
        Scanner kb = new Scanner(System.in);
        int n=kb.nextInt();
        int k=kb.nextInt();
        int[] arr=new int[n];
        for(int i=0; i<n; i++){
            arr[i]=kb.nextInt();
        }
        for(int x : T.solution(n, k, arr)) System.out.print(x+" ");
    }
}