백준 1780번: 종이의 개수

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

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.StringTokenizer;
 
public class Main {
    private static int[][] arr;
    private static int[] num = new int[3];    // -1, 0 ,1
    
    public static void main(String[] args) throws NumberFormatException, IOException {
        BufferedReader reader = new BufferedReader(new InputStreamReader(System.in));
        
        int N = Integer.parseInt(reader.readLine());
        arr = new int[N][N];
        
        for(int i=0 ; i<N ; i++){
            StringTokenizer tokenizer = new StringTokenizer(reader.readLine());
            for(int j=0 ; j<N ; j++){
                arr[i][j] = Integer.parseInt(tokenizer.nextToken());
            }
        }
        
        cut(N, 0, 0);
        
        for(int i=0 ; i<3 ; i++)
            System.out.println(num[i]);
    }
    
    public static boolean equal(int size, int startX, int startY){
        int target = arr[startY][startX];
        
        for(int i=startY ; i<startY+size ; i++){
            for(int j=startX ; j<startX+size ; j++){
                if(target != arr[i][j]){
                    return false;
                }
            }
        }
        
        num[target+1]++;
        return true;
    }
    
    public static void cut(int size, int startX, int startY){
        if(equal(size, startX, startY))
            return;
        
        for(int i=0 ; i<3 ; i++)
            for(int j=0 ; j<3 ; j++)
                cut(size/3, startX + j*(size/3), startY + i*(size/3));
    }
}