1780번 종이의 개수

https://www.acmicpc.net/problem/1780

분할 정복이다.

셈하는 것은 HashMap으로 하였다.

import java.io.*;
import java.util.*;
 
public class Main {
    
    static int n, minus = 0, zero = 0, one = 0;
    static int m[][];
    static HashMap<Integer, Integer> hm = new HashMap<Integer, Integer>();
    
    static boolean chk(int r, int c, int len)
    {
        int num = m[r][c];
        
        for(int i=r; i<r+len; i++) {
            for(int j=c; j<c+len; j++) {
                if(num != m[i][j]) {
                    return false;
                }
            }
        }
        
        return true;
    }
    
    static void simulation(int r, int c, int len)
    {    
        if(chk(r, c, len)) {        
            hm.put(m[r][c], hm.get(m[r][c]) + 1);
            return;
        }
                
        for(int i=0; i<3; i++) {
            for(int j=0; j<3; j++) {
                int y = r + (len/3)*i;
                int x = c + (len/3)*j;
                simulation(y, x, len/3);
            }
        }    
    }
    
    public static void main(String[] args) throws IOException {
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        BufferedWriter bw = new BufferedWriter(new OutputStreamWriter(System.out));
        StringTokenizer st;
        
        hm.put(-1, 0);
        hm.put(0, 0);
        hm.put(1, 0);
        
        n = Integer.parseInt(br.readLine());
        m = new int[n+1][n+1];
        
        for(int i=0; i<n; i++) {
            st = new StringTokenizer(br.readLine());
            for(int j=0; j<n; j++) {
                m[i][j] = Integer.parseInt(st.nextToken());
            }
        }    
        
        simulation(0, 0, n);
        
        for(int i=-1; i<=1; i++) {
            bw.write(String.valueOf(hm.get(i)) + "\n");
        }
        
        bw.flush();
        bw.close();
    }
}